$BXMT
BLACKSTONE MORTGAGE TRUST, INC. Stock $bxmt

$bxmt Overview Financials Valuation SEC Filings Company Website

2024 Q3 Form 10-Q Financial Statement

#000106163024000116 Filed on July 24, 2024

Income Statement

Concept	2024 Q3	2024 Q2	2023 Q2
Revenue	$430.1M	$466.2M	$521.9M
YoY Change	-17.19%	-10.68%	83.97%
Cost Of Revenue	$340.3M	$358.1M	$377.4M
YoY Change	-11.1%	-5.1%	130.54%
Gross Profit	$89.74M	$108.0M	$144.5M
YoY Change	-34.25%	-25.24%	20.44%
Gross Profit Margin	20.87%	23.18%	27.69%
Selling, General & Admin	$14.42M	$13.66M	$10.96M
YoY Change	35.48%	24.68%	-1.4%
% of Gross Profit	16.07%	12.64%	7.58%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$1.029M	$185.0K
YoY Change
% of Gross Profit	1.15%	0.17%
Operating Expenses	$148.6M	$13.66M	$13.02M
YoY Change	1138.04%	4.9%	4.94%
Operating Profit	-$58.83M	$94.39M	$131.5M
YoY Change	-147.26%	-28.23%	22.22%
Interest Expense			$344.5M
YoY Change			152.2%
% of Operating Profit			262.0%
Other Income/Expense, Net
YoY Change
Pretax Income	-$55.23M	-$58.99M	$103.7M
YoY Change	-271.91%	-156.88%	9.61%
Income Tax	$613.0K	$1.200M	$1.202M
% Of Pretax Income			1.16%
Net Earnings	-$56.38M	-$61.06M	$101.7M
YoY Change	-290.98%	-160.07%	9.01%
Net Earnings / Revenue	-13.11%	-13.1%	19.48%
Basic Earnings Per Share	-$0.32	-$0.35	$0.59
Diluted Earnings Per Share	-$0.32	-$0.35	$0.56
COMMON SHARES
Basic Shares Outstanding	173.6M shares	173.6M shares	172.3M shares
Diluted Shares Outstanding	173.6M shares	174.0M shares	180.9M shares

Balance Sheet

Concept	2024 Q3	2024 Q2	2023 Q2
SHORT-TERM ASSETS
Cash & Short-Term Investments	$322.1M	$373.9M	$482.9M
YoY Change	-23.58%	-22.57%	70.27%
Cash & Equivalents	$322.1M	$373.9M	$482.9M
Short-Term Investments
Other Short-Term Assets	$132.0M	$650.0K	$49.68M
YoY Change	107.26%	-98.69%	-80.38%
Inventory
Prepaid Expenses
Receivables	$176.0M	$196.8M	$188.8M
Other Receivables	$0.00	$0.00	$0.00
Total Short-Term Assets	$630.1M	$373.9M	$721.4M
YoY Change	-6.62%	-48.17%	9.26%
LONG-TERM ASSETS
Property, Plant & Equipment	$138.7M	$60.02M
YoY Change
Goodwill
YoY Change
Intangibles
YoY Change
Long-Term Investments
YoY Change
Other Assets
YoY Change
Total Long-Term Assets	$20.81B	$22.26B	$24.14B
YoY Change	-10.94%	-7.78%	-2.59%
TOTAL ASSETS
Total Short-Term Assets	$630.1M	$373.9M	$721.4M
Total Long-Term Assets	$20.81B	$22.26B	$24.14B
Total Assets	$21.44B	$22.64B	$24.86B
YoY Change	-10.81%	-8.95%	-2.28%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$8.662M	$6.365M	$8.717M
YoY Change	11.88%	-26.98%	10.36%
Accrued Expenses	$92.77M	$108.9M	$105.4M
YoY Change	-6.86%	3.36%	27.93%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$16.27M
YoY Change	-100.0%	-100.0%	92.93%
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$182.7M	$223.0M	$237.2M
YoY Change	-19.78%	-6.02%	16.11%
LONG-TERM LIABILITIES
Long-Term Debt	$17.24B	$18.37B	$20.00B
YoY Change	-10.56%	-8.14%	-2.67%
Other Long-Term Liabilities	$163.6M	$257.3M	$56.78M
YoY Change	225.78%	353.17%	129.81%
Total Long-Term Liabilities	$17.40B	$18.63B	$20.06B
YoY Change	-9.95%	-7.12%	-2.51%
TOTAL LIABILITIES
Total Short-Term Liabilities	$182.7M	$223.0M	$237.2M
Total Long-Term Liabilities	$17.40B	$18.63B	$20.06B
Total Liabilities	$17.58B	$18.63B	$20.32B
YoY Change	-10.06%	-8.32%	-2.21%
SHAREHOLDERS EQUITY
Retained Earnings	-$1.690B	-$1.552B	-$963.4M
YoY Change	62.31%	61.05%	18.72%
Common Stock	$5.523B	$5.526B	$5.493B
YoY Change	0.4%	0.59%	0.94%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$3.845B	$3.985B	$4.541B
YoY Change
Total Liabilities & Shareholders Equity	$21.44B	$22.64B	$24.86B
YoY Change	-10.81%	-8.95%	-2.28%

Cashflow Statement

Concept	2024 Q3	2024 Q2	2023 Q2
OPERATING ACTIVITIES
Net Income	-$56.38M	-$61.06M	$101.7M
YoY Change	-290.98%	-160.07%	9.01%
Depreciation, Depletion And Amortization	$1.029M	$185.0K
YoY Change
Cash From Operating Activities	$87.12M	$100.2M	$127.9M
YoY Change	-21.51%	-21.67%	36.79%
INVESTING ACTIVITIES
Capital Expenditures
YoY Change
Acquisitions
YoY Change
Other Investing Activities	$1.286B	$488.1M	$582.1M
YoY Change	186.81%	-16.16%	-133.93%
Cash From Investing Activities	$1.286B	$488.1M	$582.1M
YoY Change	186.81%	-16.16%	-133.93%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-1.426B	-628.4M	-744.8M
YoY Change	130.41%	-15.62%	-146.43%
NET CHANGE
Cash From Operating Activities	87.12M	100.2M	127.9M
Cash From Investing Activities	1.286B	488.1M	582.1M
Cash From Financing Activities	-1.426B	-628.4M	-744.8M
Net Change In Cash	-52.92M	-40.20M	-34.75M
YoY Change	-11.13%	15.69%	92.3%
FREE CASH FLOW
Cash From Operating Activities	$87.12M	$100.2M	$127.9M
Capital Expenditures
Free Cash Flow
YoY Change

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2023Q2	us-gaap	Noninterest Expense NoninterestExpense	45837000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	152408000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	21494000	usd
	us-gaap	Interest Paid Net InterestPaidNet	667527000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	2020000	usd
	bxmt	Loan Principal Payments Held By Servicer LoanPrincipalPaymentsHeldByServicer	0	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	loan
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	20814030000	usd
CY2023Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13022000	usd
CY2024Q2	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	usd
CY2023Q2	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	2963000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2023	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2023	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2023	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2023	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2023	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2023	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2024Q2	bxmt	Loan Participations Sold Liability Amount LoanParticipationsSoldLiabilityAmount	100442000	usd
	us-gaap	Debt Instrument Variable Interest Rate Type Extensible Enumeration DebtInstrumentVariableInterestRateTypeExtensibleEnumeration	http://fasb.org/us-gaap/2024#SecuredOvernightFinancingRateSofrMember
CY2024Q2	us-gaap	Secured Debt SecuredDebt	2095199000	usd
CY2024Q2	bxmt	Loan Participations Sold Liability Amount LoanParticipationsSoldLiabilityAmount	100442000	usd
CY2024Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	466152000	usd
CY2023Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	521892000	usd
	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	952275000	usd
CY2024Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	126772000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	269165000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	351530000	usd
CY2024Q2	us-gaap	Noninterest Expense NoninterestExpense	32386000	usd
CY2023Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	103699000	usd
	us-gaap	Noninterest Expense NoninterestExpense	65041000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-181153000	usd
CY2023Q2	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	27807000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1217000	usd
CY2023Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1202000	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	usd
CY2024Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	-963000	usd
CY2023Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
CY2024Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-58985000	usd
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
CY2024Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	855000	usd
CY2023Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	846000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Net Income Loss NetIncomeLoss	-61057000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1217000	usd
	us-gaap	Management Fee Expense ManagementFeeExpense	37653000	usd
	us-gaap	Management Fee Expense ManagementFeeExpense	63865000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	25887000	usd
CY2023Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1202000	usd
CY2023Q4	bxmt	Loan Participations Sold Liability Amount LoanParticipationsSoldLiabilityAmount	337179000	usd
CY2024Q2	us-gaap	Secured Debt SecuredDebt	2095199000	usd
CY2023Q4	us-gaap	Secured Debt SecuredDebt	2101632000	usd
CY2024Q2	us-gaap	Convertible Notes Payable ConvertibleNotesPayable	296486000	usd
CY2023Q4	us-gaap	Convertible Notes Payable ConvertibleNotesPayable	295847000	usd
CY2024Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	466152000	usd
CY2024Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	339380000	usd
CY2023Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	344549000	usd
	us-gaap	Interest Expense Operating InterestExpenseOperating	683110000	usd
	us-gaap	Interest Expense Operating InterestExpenseOperating	661746000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	269165000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	351530000	usd
CY2024Q2	us-gaap	Management Fee Expense ManagementFeeExpense	18726000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2219000	usd
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Management Fee Expense ManagementFeeExpense	32815000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	usd
CY2024Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	-963000	usd
CY2023Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	-963000	usd
	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
CY2024Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-58985000	usd
CY2023Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	103699000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-181153000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	224148000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
CY2024Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	855000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Net Income Loss NetIncomeLoss	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss NetIncomeLoss	101651000	usd
	us-gaap	Net Income Loss NetIncomeLoss	-184895000	usd
	us-gaap	Net Income Loss NetIncomeLoss	219408000	usd
CY2023Q4	us-gaap	Secured Debt SecuredDebt	2101632000	usd
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2024Q2	us-gaap	Convertible Notes Payable ConvertibleNotesPayable	296486000	usd
CY2023Q4	us-gaap	Convertible Notes Payable ConvertibleNotesPayable	295847000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
CY2024Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	855000	usd
CY2023Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	846000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1523000	usd
CY2024Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	466152000	usd
CY2023Q2	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	521892000	usd
	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	952275000	usd
	us-gaap	Interest And Fee Income Loans And Leases InterestAndFeeIncomeLoansAndLeases	1013276000	usd
CY2024Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	339380000	usd
CY2023Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	344549000	usd
	us-gaap	Interest Expense Operating InterestExpenseOperating	683110000	usd
	us-gaap	Interest Expense Operating InterestExpenseOperating	661746000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	269165000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	351530000	usd
	us-gaap	Management Fee Expense ManagementFeeExpense	63865000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	27388000	usd
	us-gaap	Noninterest Expense NoninterestExpense	89752000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Net Income Loss NetIncomeLoss	-61057000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	387277000	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	usd
CY2024Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	-963000	usd
CY2023Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	-963000	usd
CY2024Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-58985000	usd
CY2023Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	103699000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1217000	usd
CY2023Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1202000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2219000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3095000	usd
CY2023Q2	us-gaap	Net Income Loss NetIncomeLoss	101651000	usd
	us-gaap	Net Income Loss NetIncomeLoss	-184895000	usd
	us-gaap	Net Income Loss NetIncomeLoss	219408000	usd
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2024Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.35
CY2023Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.06
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
	us-gaap	Interest Expense Operating InterestExpenseOperating	661746000	usd
CY2023Q2	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	177343000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	3668000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	28469000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	269165000	usd
	us-gaap	Interest Income Expense Net InterestIncomeExpenseNet	351530000	usd
CY2024Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13660000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	-42064000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	50328000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	27388000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	37630000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-3210000	usd
CY2024Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	-963000	usd
CY2023Q2	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
	bxmt	Net Income Expense From Real Estate Owned NetIncomeExpenseFromRealEstateOwned	0	usd
CY2024Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-58985000	usd
CY2023Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	103699000	usd
	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	224148000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1217000	usd
CY2023Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1202000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2219000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3095000	usd
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
CY2024Q2	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	855000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Net Income Loss NetIncomeLoss	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss NetIncomeLoss	101651000	usd
	us-gaap	Net Income Loss NetIncomeLoss	-184895000	usd
	us-gaap	Net Income Loss NetIncomeLoss	219408000	usd
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2024Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.35
CY2023Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.06
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180886445	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-25557000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	42938000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-49609000	usd
	us-gaap	Net Income Loss NetIncomeLoss	-184895000	usd
	us-gaap	Net Income Loss NetIncomeLoss	219408000	usd
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2024Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.35
CY2023Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.06
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180886445	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	3668000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	28469000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	-42064000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	50328000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-3210000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-25557000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	42938000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-49609000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	874000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	719000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-59744000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	105409000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-182498000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	221772000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	855000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	846000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-60599000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	104563000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-184021000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	220127000	usd
CY2023Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4387504000	usd
CY2024Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7911000	usd
CY2024Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q1	us-gaap	Profit Loss ProfitLoss	-123170000	usd
CY2024Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	416000	usd
CY2024Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q1	us-gaap	Dividends Dividends	107901000	usd
CY2024Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	627000	usd
CY2024Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7761000	usd
CY2024Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	261000	usd
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2024Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.35
CY2023Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.06
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180886445	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180877974	shares
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	3668000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	28469000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	-42064000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	50328000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-3210000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-25557000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	42938000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-49609000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	874000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	719000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-59744000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	105409000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-182498000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	855000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	846000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-60599000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	104563000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-184021000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	220127000	usd
CY2024Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7911000	usd
CY2024Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	253000	usd
CY2024Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q1	us-gaap	Profit Loss ProfitLoss	-123170000	usd
CY2024Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	416000	usd
CY2024Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q1	us-gaap	Dividends Dividends	107901000	usd
CY2024Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	627000	usd
CY2024Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4164587000	usd
CY2024Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7761000	usd
CY2024Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	261000	usd
CY2024Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q2	us-gaap	Profit Loss ProfitLoss	-60202000	usd
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180886445	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180877974	shares
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	3668000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	28469000	usd
	us-gaap	Other Comprehensive Income Foreign Currency Transaction And Translation Gain Loss Arising During Period Net Of Tax OtherComprehensiveIncomeForeignCurrencyTransactionAndTranslationGainLossArisingDuringPeriodNetOfTax	50328000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-3210000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	42938000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification After Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAfterTax	-49609000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	719000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-59744000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	105409000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-182498000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	221772000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	855000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	846000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-60599000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	104563000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-184021000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	220127000	usd
CY2024Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7911000	usd
CY2024Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	253000	usd
CY2024Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q1	us-gaap	Profit Loss ProfitLoss	-123170000	usd
CY2024Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	416000	usd
CY2024Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q1	us-gaap	Dividends Dividends	107901000	usd
CY2024Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	627000	usd
CY2024Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4164587000	usd
CY2024Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7761000	usd
CY2024Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	261000	usd
CY2024Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Noncontrolling Interest Increase From Subsidiary Equity Issuance NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	1245000	usd
CY2024Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	1840000	usd
CY2024Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4004598000	usd
CY2023Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	287000	usd
CY2023Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	163000	usd
CY2023Q1	us-gaap	Profit Loss ProfitLoss	118556000	usd
CY2023Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-2194000	usd
CY2023Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q1	us-gaap	Dividends Dividends	107072000	usd
CY2023Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	733000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	874000	usd
	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	719000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-59744000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	105409000	usd
	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	-182498000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	855000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	846000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1523000	usd
	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	1645000	usd
CY2024Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	-60599000	usd
CY2023Q2	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	104563000	usd
	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	220127000	usd
CY2023Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4387504000	usd
CY2024Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7911000	usd
CY2024Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	253000	usd
CY2024Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q1	us-gaap	Profit Loss ProfitLoss	-123170000	usd
CY2024Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	627000	usd
CY2024Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4164587000	usd
CY2024Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7761000	usd
CY2024Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	261000	usd
CY2024Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	201000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Dividends Dividends	107873000	usd
CY2024Q2	us-gaap	Noncontrolling Interest Increase From Subsidiary Equity Issuance NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	1245000	usd
CY2024Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	1840000	usd
CY2024Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4004598000	usd
CY2022Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4544200000	usd
CY2023Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	287000	usd
CY2023Q1	us-gaap	Profit Loss ProfitLoss	118556000	usd
CY2023Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-2194000	usd
CY2023Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	733000	usd
CY2023Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4560699000	usd
CY2023Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	235000	usd
CY2023Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	173000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Dividends Dividends	107028000	usd
CY2023Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	791000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	15320000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	43697000	usd
	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	29605000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	6164000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	2432000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	387277000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	37630000	usd
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	185000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	458000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Dividends Dividends	107873000	usd
CY2024Q2	us-gaap	Noncontrolling Interest Increase From Subsidiary Equity Issuance NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	1245000	usd
CY2024Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	1840000	usd
CY2022Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4544200000	usd
CY2023Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	287000	usd
CY2023Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	163000	usd
CY2023Q1	us-gaap	Profit Loss ProfitLoss	118556000	usd
CY2023Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-2194000	usd
CY2023Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q1	us-gaap	Dividends Dividends	107072000	usd
CY2023Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4560699000	usd
CY2023Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	235000	usd
CY2023Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	173000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Dividends Dividends	107028000	usd
CY2023Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4566189000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	16074000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	43697000	usd
	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	29605000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	6164000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	2432000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	387277000	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	2963000	usd
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	185000	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-291000	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-1366000	usd
	bxmt	Realized Gains Losses On Derivative Financial Instruments Net RealizedGainsLossesOnDerivativeFinancialInstrumentsNet	16926000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-20257000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-5628000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-15431000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-11912000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	194793000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	235635000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	626746000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	713075000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1413348000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1491158000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	11774000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	8088000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	77368000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	164342000	usd
	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	55760000	usd
	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	25176000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	63110000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	163610000	usd
	bxmt	Proceeds From Collateral Deposit On Derivative Instrument Investing Activities ProceedsFromCollateralDepositOnDerivativeInstrumentInvestingActivities	150710000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	235960000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	0	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Dividends Dividends	107873000	usd
CY2024Q2	us-gaap	Noncontrolling Interest Increase From Subsidiary Equity Issuance NoncontrollingInterestIncreaseFromSubsidiaryEquityIssuance	1245000	usd
CY2024Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	1840000	usd
CY2024Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4004598000	usd
CY2022Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4544200000	usd
CY2023Q1	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q1	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	287000	usd
CY2023Q1	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	163000	usd
CY2023Q1	us-gaap	Profit Loss ProfitLoss	118556000	usd
CY2023Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	-2194000	usd
CY2023Q1	us-gaap	Dividends Dividends	107072000	usd
CY2023Q1	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	733000	usd
CY2023Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4560699000	usd
CY2023Q2	us-gaap	Adjustments To Additional Paid In Capital Share Based Compensation Restricted Stock Units Requisite Service Period Recognition AdjustmentsToAdditionalPaidInCapitalShareBasedCompensationRestrictedStockUnitsRequisiteServicePeriodRecognition	7492000	usd
CY2023Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	235000	usd
CY2023Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	173000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Dividends Dividends	107028000	usd
CY2023Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4566189000	usd
	us-gaap	Profit Loss ProfitLoss	-183372000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	29605000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	6164000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	2432000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	387277000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	37630000	usd
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	185000	usd
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	0	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-291000	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-1366000	usd
	bxmt	Realized Gains Losses On Derivative Financial Instruments Net RealizedGainsLossesOnDerivativeFinancialInstrumentsNet	16926000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-20257000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-5628000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-15431000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-11912000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	194793000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	235635000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	626746000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	713075000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1413348000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1491158000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	11774000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	8088000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	77368000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	164342000	usd
	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	55760000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	63110000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	163610000	usd
	bxmt	Proceeds From Collateral Deposit On Derivative Instrument Investing Activities ProceedsFromCollateralDepositOnDerivativeInstrumentInvestingActivities	150710000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	235960000	usd
CY2023Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4560699000	usd
CY2023Q2	us-gaap	Stock Issued During Period Value Dividend Reinvestment Plan StockIssuedDuringPeriodValueDividendReinvestmentPlan	235000	usd
CY2023Q2	bxmt	Adjustments To Additional Paid In Capital Deferred Compensation AdjustmentsToAdditionalPaidInCapitalDeferredCompensation	173000	usd
CY2023Q2	us-gaap	Profit Loss ProfitLoss	102497000	usd
CY2023Q2	us-gaap	Other Comprehensive Income Loss Net Of Tax OtherComprehensiveIncomeLossNetOfTax	2912000	usd
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Dividends Dividends	107028000	usd
CY2023Q2	us-gaap	Minority Interest Decrease From Distributions To Noncontrolling Interest Holders MinorityInterestDecreaseFromDistributionsToNoncontrollingInterestHolders	791000	usd
CY2023Q2	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4566189000	usd
	us-gaap	Profit Loss ProfitLoss	221053000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	15320000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	6164000	usd
	bxmt	Payment In Kind Interest Net Of Interest Received PaymentInKindInterestNetOfInterestReceived	2432000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	387277000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Credit Loss Expense Reversal FinancingReceivableExcludingAccruedInterestCreditLossExpenseReversal	37630000	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	2963000	usd
	us-gaap	Gains Losses On Extinguishment Of Debt GainsLossesOnExtinguishmentOfDebt	0	usd
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	185000	usd
	us-gaap	Depreciation Nonproduction DepreciationNonproduction	0	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-291000	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-1366000	usd
	bxmt	Realized Gains Losses On Derivative Financial Instruments Net RealizedGainsLossesOnDerivativeFinancialInstrumentsNet	9155000	usd
	bxmt	Realized Gains Losses On Derivative Financial Instruments Net RealizedGainsLossesOnDerivativeFinancialInstrumentsNet	16926000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-20257000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-15431000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-11912000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	194793000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	235635000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	713075000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1413348000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	11774000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	77368000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	164342000	usd
	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	55760000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	63110000	usd
	bxmt	Proceeds From Collateral Deposit On Derivative Instrument Investing Activities ProceedsFromCollateralDepositOnDerivativeInstrumentInvestingActivities	150710000	usd
	bxmt	Proceeds From Collateral Deposit On Derivative Instrument Investing Activities ProceedsFromCollateralDepositOnDerivativeInstrumentInvestingActivities	257700000	usd
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	864368000	usd
	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	741095000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	235960000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	0	usd
	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	13734000	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	2467000	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	1524000	usd
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	213272000	usd
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-788499000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	291340000	usd
	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	3285000	usd
	us-gaap	Interest Paid Net InterestPaidNet	639090000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	4290000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	106832000	usd
	bxmt	Loan Principal Payments Held By Servicer LoanPrincipalPaymentsHeldByServicer	12272000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-291000	usd
	us-gaap	Derivative Gain Loss On Derivative Net DerivativeGainLossOnDerivativeNet	-1366000	usd
	bxmt	Realized Gains Losses On Derivative Financial Instruments Net RealizedGainsLossesOnDerivativeFinancialInstrumentsNet	9155000	usd
	bxmt	Realized Gains Losses On Derivative Financial Instruments Net RealizedGainsLossesOnDerivativeFinancialInstrumentsNet	16926000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-20257000	usd
	us-gaap	Increase Decrease In Other Operating Assets IncreaseDecreaseInOtherOperatingAssets	-5628000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-15431000	usd
	us-gaap	Increase Decrease In Other Operating Liabilities IncreaseDecreaseInOtherOperatingLiabilities	-11912000	usd
	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	194793000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	626746000	usd
	us-gaap	Payments For Proceeds From Loans Receivable PaymentsForProceedsFromLoansReceivable	713075000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1413348000	usd
	us-gaap	Proceeds From Sale And Collection Of Loans Receivable ProceedsFromSaleAndCollectionOfLoansReceivable	1491158000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	11774000	usd
	bxmt	Proceeds From Loan Origination And Other Loan Receivable Fees ProceedsFromLoanOriginationAndOtherLoanReceivableFees	8088000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	77368000	usd
	us-gaap	Payments For Derivative Instrument Investing Activities PaymentsForDerivativeInstrumentInvestingActivities	164342000	usd
	us-gaap	Proceeds From Derivative Instrument Investing Activities ProceedsFromDerivativeInstrumentInvestingActivities	55760000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	63110000	usd
	bxmt	Payments For Collateral Deposit On Derivative Instrument Investing Activities PaymentsForCollateralDepositOnDerivativeInstrumentInvestingActivities	163610000	usd
	bxmt	Proceeds From Collateral Deposit On Derivative Instrument Investing Activities ProceedsFromCollateralDepositOnDerivativeInstrumentInvestingActivities	150710000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	235960000	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	0	usd
	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	14674000	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	1245000	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	2467000	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	1524000	usd
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	213272000	usd
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-788499000	usd
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	188231000	usd
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	350014000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	291340000	usd
CY2023Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	482856000	usd
	us-gaap	Interest Paid Net InterestPaidNet	639090000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
	bxmt	Loan Principal Payments Held By Servicer LoanPrincipalPaymentsHeldByServicer	12272000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	usd
	bxmt	Repayments Of Loan Participations RepaymentsOfLoanParticipations	0	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	1245000	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	2467000	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	1524000	usd
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	215068000	usd
	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	213272000	usd
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1032778000	usd
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-788499000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	291340000	usd
	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	-2521000	usd
	us-gaap	Effect Of Exchange Rate On Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents EffectOfExchangeRateOnCashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	3285000	usd
CY2023Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	482856000	usd
	us-gaap	Interest Paid Net InterestPaidNet	639090000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	4290000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	106832000	usd
	bxmt	Loan Principal Payments Held By Servicer LoanPrincipalPaymentsHeldByServicer	12272000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	usd
	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="margin-top:12pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Certain reclassifications have been made in the presentation of the prior period statement of cash flows related to payment-in-kind interest and principal fundings of loans receivable, and in new financings by spread in Note 6 to conform to the current period presentation.</span></div>
	us-gaap	Payments Of Financing Costs PaymentsOfFinancingCosts	13734000	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	1245000	usd
	us-gaap	Proceeds From Minority Shareholders ProceedsFromMinorityShareholders	0	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	2467000	usd
	us-gaap	Payments To Minority Shareholders PaymentsToMinorityShareholders	1524000	usd
	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-788499000	usd
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	26383000	usd
	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Excluding Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseExcludingExchangeRateEffect	188231000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	291340000	usd
CY2024Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	373876000	usd
CY2023Q2	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	482856000	usd
	us-gaap	Interest Paid Net InterestPaidNet	639090000	usd
	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	4290000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	106832000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="margin-top:12pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Certain reclassifications have been made in the presentation of the prior period statement of cash flows related to payment-in-kind interest and principal fundings of loans receivable, and in new financings by spread in Note 6 to conform to the current period presentation.</span></div>
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	0	usd
	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="margin-top:12pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Certain reclassifications have been made in the presentation of the prior period statement of cash flows related to payment-in-kind interest and principal fundings of loans receivable, and in new financings by spread in Note 6 to conform to the current period presentation.</span></div>
	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Use of Estimates</span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">The preparation of consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may ultimately differ materially from those estimates.</span></div>
	us-gaap	Revenue Recognition Interest RevenueRecognitionInterest	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Revenue Recognition </span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Interest income from our loans receivable portfolio is recognized over the life of each loan using the effective interest method and is recorded on the accrual basis. Recognition of fees, premiums, and discounts associated with these investments is deferred and recorded over the term of the loan as an adjustment to yield. Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in our opinion, recovery of income and principal becomes doubtful. Interest received is then recorded as income or as a reduction in the amortized cost basis, based on the specific facts and circumstances, until accrual is resumed when the loan becomes contractually current and performance is demonstrated to be resumed. In addition, for loans we originate, the related origination expenses are deferred and recognized as a reduction to interest income, however expenses related to loans we acquire are included in general and administrative expenses as incurred.</span></div>
	us-gaap	Prior Period Reclassification Adjustment Description PriorPeriodReclassificationAdjustmentDescription	<div style="margin-top:12pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Certain reclassifications have been made in the presentation of the prior period statement of cash flows related to payment-in-kind interest and principal fundings of loans receivable, and in new financings by spread in Note 6 to conform to the current period presentation.</span></div>
	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Use of Estimates</span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">The preparation of consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may ultimately differ materially from those estimates.</span></div>
	us-gaap	Revenue Recognition Interest RevenueRecognitionInterest	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Revenue Recognition </span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Interest income from our loans receivable portfolio is recognized over the life of each loan using the effective interest method and is recorded on the accrual basis. Recognition of fees, premiums, and discounts associated with these investments is deferred and recorded over the term of the loan as an adjustment to yield. Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in our opinion, recovery of income and principal becomes doubtful. Interest received is then recorded as income or as a reduction in the amortized cost basis, based on the specific facts and circumstances, until accrual is resumed when the loan becomes contractually current and performance is demonstrated to be resumed. In addition, for loans we originate, the related origination expenses are deferred and recognized as a reduction to interest income, however expenses related to loans we acquire are included in general and administrative expenses as incurred.</span></div>
	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Use of Estimates</span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">The preparation of consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may ultimately differ materially from those estimates.</span></div>
	us-gaap	Revenue Recognition Interest RevenueRecognitionInterest	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Revenue Recognition </span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Interest income from our loans receivable portfolio is recognized over the life of each loan using the effective interest method and is recorded on the accrual basis. Recognition of fees, premiums, and discounts associated with these investments is deferred and recorded over the term of the loan as an adjustment to yield. Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in our opinion, recovery of income and principal becomes doubtful. Interest received is then recorded as income or as a reduction in the amortized cost basis, based on the specific facts and circumstances, until accrual is resumed when the loan becomes contractually current and performance is demonstrated to be resumed. In addition, for loans we originate, the related origination expenses are deferred and recognized as a reduction to interest income, however expenses related to loans we acquire are included in general and administrative expenses as incurred.</span></div>
CY2023Q4	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	471300000	usd
CY2023Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	640600000	usd
	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Use of Estimates</span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">The preparation of consolidated financial statements in conformity with GAAP requires us to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results may ultimately differ materially from those estimates.</span></div>
	us-gaap	Revenue Recognition Interest RevenueRecognitionInterest	<div style="margin-top:18pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:115%">Revenue Recognition </span></div><div style="margin-top:6pt;text-align:justify"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:115%">Interest income from our loans receivable portfolio is recognized over the life of each loan using the effective interest method and is recorded on the accrual basis. Recognition of fees, premiums, and discounts associated with these investments is deferred and recorded over the term of the loan as an adjustment to yield. Income accrual is generally suspended for loans at the earlier of the date at which payments become 90 days past due or when, in our opinion, recovery of income and principal becomes doubtful. Interest received is then recorded as income or as a reduction in the amortized cost basis, based on the specific facts and circumstances, until accrual is resumed when the loan becomes contractually current and performance is demonstrated to be resumed. In addition, for loans we originate, the related origination expenses are deferred and recognized as a reduction to interest income, however expenses related to loans we acquire are included in general and administrative expenses as incurred.</span></div>
CY2023Q4	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	471300000	usd
CY2023Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	640600000	usd
CY2024Q2	bxmt	Real Estate Owned Number Of Assets Classified As Held For Sale RealEstateOwnedNumberOfAssetsClassifiedAsHeldForSale	1	real_estate_owned_asset
CY2023Q4	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	471300000	usd
CY2023Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	640600000	usd
CY2024Q2	bxmt	Real Estate Owned Number Of Assets Classified As Held For Sale RealEstateOwnedNumberOfAssetsClassifiedAsHeldForSale	1	real_estate_owned_asset
CY2023Q4	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Restricted Cash RestrictedCash	0	usd
CY2024Q2	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	471300000	usd
CY2023Q4	us-gaap	Fair Value Disclosure Offbalance Sheet Risks Amount Asset FairValueDisclosureOffbalanceSheetRisksAmountAsset	640600000	usd
CY2024Q2	bxmt	Real Estate Owned Number Of Assets Classified As Held For Sale RealEstateOwnedNumberOfAssetsClassifiedAsHeldForSale	1	real_estate_owned_asset
CY2024Q2	bxmt	Real Estate Owned Number Of Assets Classified As Held For Sale RealEstateOwnedNumberOfAssetsClassifiedAsHeldForSale	1	real_estate_owned_asset
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	security_loan
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	security_loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2024Q2	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0335
CY2023Q4	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0337
	bxmt	Financing Receivable Basis Spread On Variable Rate Weighted Average All In Yield FinancingReceivableBasisSpreadOnVariableRateWeightedAverageAllInYield	0.0367
	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y1M6D
CY2023	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y4M24D
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansSubjectToPrepaymentRestrictions	0.12
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.88
CY2023Q4	bxmt	Financing Receivable Percent Of Loans Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansSubjectToPrepaymentRestrictions	0.14
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	security_loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0335
CY2023Q4	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0337
	bxmt	Financing Receivable Basis Spread On Variable Rate Weighted Average All In Yield FinancingReceivableBasisSpreadOnVariableRateWeightedAverageAllInYield	0.0367
CY2023	bxmt	Financing Receivable Basis Spread On Variable Rate Weighted Average All In Yield FinancingReceivableBasisSpreadOnVariableRateWeightedAverageAllInYield	0.0371
	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y1M6D
CY2023	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y4M24D
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansSubjectToPrepaymentRestrictions	0.12
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.88
CY2023Q4	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.86
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-136707000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	security_loan
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	security_loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0335
CY2023Q4	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0337
	bxmt	Financing Receivable Basis Spread On Variable Rate Weighted Average All In Yield FinancingReceivableBasisSpreadOnVariableRateWeightedAverageAllInYield	0.0367
CY2023	bxmt	Financing Receivable Basis Spread On Variable Rate Weighted Average All In Yield FinancingReceivableBasisSpreadOnVariableRateWeightedAverageAllInYield	0.0371
	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y1M6D
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansSubjectToPrepaymentRestrictions	0.12
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.88
CY2023Q4	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.86
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-136707000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	bxmt	Financing Receivable Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1225525000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	35361000	usd
	bxmt	Financing Receivable Before Allowance For Credit Loss Fee And Loan In Process Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableBeforeAllowanceForCreditLossFeeAndLoanInProcessSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1260886000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcessWriteoff	85318000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Writeoff FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountWriteoff	11768000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossWriteoff	73550000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	security_loan
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	security_loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0335
CY2023Q4	us-gaap	Loans Receivable Basis Spread On Variable Rate LoansReceivableBasisSpreadOnVariableRate	0.0337
	bxmt	Financing Receivable Basis Spread On Variable Rate Weighted Average All In Yield FinancingReceivableBasisSpreadOnVariableRateWeightedAverageAllInYield	0.0367
	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y1M6D
CY2023	bxmt	Mortgage Loan On Real Estate Final Maturity Term MortgageLoanOnRealEstateFinalMaturityTerm	P2Y4M24D
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansSubjectToPrepaymentRestrictions	0.12
CY2024Q2	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.88
CY2023Q4	bxmt	Financing Receivable Percent Of Loans Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansSubjectToPrepaymentRestrictions	0.14
CY2023Q4	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.86
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-136707000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	bxmt	Financing Receivable Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1225525000	usd
	bxmt	Financing Receivable Before Allowance For Credit Loss Fee And Loan In Process Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableBeforeAllowanceForCreditLossFeeAndLoanInProcessSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1260886000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcessWriteoff	85318000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Writeoff FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountWriteoff	11768000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossWriteoff	73550000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
CY2023Q4	bxmt	Financing Receivable Percent Of Loans Not Subject To Prepayment Restrictions FinancingReceivablePercentOfLoansNotSubjectToPrepaymentRestrictions	0.86
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-136707000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	bxmt	Financing Receivable Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1225525000	usd
	bxmt	Financing Receivable Before Allowance For Credit Loss Fee And Loan In Process Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableBeforeAllowanceForCreditLossFeeAndLoanInProcessSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1260886000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcessWriteoff	85318000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Writeoff FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountWriteoff	11768000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossWriteoff	73550000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	bxmt	Financing Receivable Gain Loss On Foreign Currency Translation FinancingReceivableGainLossOnForeignCurrencyTranslation	-164128000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountUnrealizedGainLossOnForeignCurrencyTranslation	-755000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossUnrealizedGainLossOnForeignCurrencyTranslation	-163373000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2024Q2	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-139812000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	20814030000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000.0	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	us-gaap	Payments To Acquire Loans Receivable PaymentsToAcquireLoansReceivable	626746000	usd
	bxmt	Financing Receivable Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1225525000	usd
	bxmt	Financing Receivable Before Allowance For Credit Loss Fee And Loan In Process Sale And Collection Of Finance Receivables And Cost Recovery Proceeds FinancingReceivableBeforeAllowanceForCreditLossFeeAndLoanInProcessSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceeds	1260886000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcessWriteoff	85318000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Writeoff FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountWriteoff	11768000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossWriteoff	73550000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	us-gaap	Transfer To Other Real Estate TransferToOtherRealEstate	60203000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Transfer To Other Assets FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossTransferToOtherAssets	10795000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountUnrealizedGainLossOnForeignCurrencyTranslation	-755000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossUnrealizedGainLossOnForeignCurrencyTranslation	-163373000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2024Q2	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-139812000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	20814030000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	loan
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	20814030000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000.0	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	us-gaap	Paid In Kind Interest PaidInKindInterest	6164000	usd
	bxmt	Financing Receivable Gain Loss On Foreign Currency Translation FinancingReceivableGainLossOnForeignCurrencyTranslation	-164128000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountUnrealizedGainLossOnForeignCurrencyTranslation	-755000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossUnrealizedGainLossOnForeignCurrencyTranslation	-163373000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2024Q2	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-139812000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	166	loan
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	20814030000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000.0	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23000000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576900000	usd
	bxmt	Financing Receivable Gain Loss On Foreign Currency Translation FinancingReceivableGainLossOnForeignCurrencyTranslation	-164128000	usd
	bxmt	Financing Receivable Unamortized Loan Fee Cost And Purchase Premium Discount Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableUnamortizedLoanFeeCostAndPurchasePremiumDiscountUnrealizedGainLossOnForeignCurrencyTranslation	-755000	usd
	bxmt	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Unrealized Gain Loss On Foreign Currency Translation FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossUnrealizedGainLossOnForeignCurrencyTranslation	-163373000	usd
	bxmt	Financing Receivable Deferred Fees And Other Items Increase Decrease FinancingReceivableDeferredFeesAndOtherItemsIncreaseDecrease	13967000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
	us-gaap	Amortization Of Deferred Loan Origination Fees Net AmortizationOfDeferredLoanOriginationFeesNet	33700000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2024Q2	us-gaap	Financing Receivable Unamortized Loan Commitment Origination Fee And Premium Discount FinancingReceivableUnamortizedLoanCommitmentOriginationFeeAndPremiumDiscount	-139812000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	20814030000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23000000000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000.0	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	22870848000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23000000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576900000	usd
CY2024Q2	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23000000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576900000	usd
CY2024Q2	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	235447000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	61013000	usd
CY2024Q1	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	751370000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	155105000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	12537000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	326137000	usd
CY2023Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	10454000	usd
CY2023Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	27284000	usd
CY2023Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	363875000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Period Increase Decrease And Writeoff Net FinancingReceivableExcludingAccruedInterestPeriodIncreaseDecreaseAndWriteoffNet	142600000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2024Q2	bxmt	Financing Receivable Number Of Impaired Loans Resolved During The Period FinancingReceivableNumberOfImpairedLoansResolvedDuringThePeriod	1	loan
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff	54048000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff	19502000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	73550000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2024Q1	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60200000	usd
CY2024Q2	bxmt	Land And Site Improvements Acquired Through Foreclosure LandAndSiteImprovementsAcquiredThroughForeclosure	40824000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	23635509000	usd
CY2023	bxmt	Financing Receivable Number Of Loans FinancingReceivableNumberOfLoans	178	loan
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLoss	23787012000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Loan Exposure FinancingReceivableExcludingAccruedInterestLoanExposure	24971028000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Net Loans Exposure Amount FinancingReceivableExcludingAccruedInterestNetLoansExposureAmount	21951988000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23000000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23900000000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	76300000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2023Q4	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	1100000000	usd
CY2023Q4	bxmt	Financing Receivable Excluding Accrued Interest Unamortized Loan Fee Cost And Purchase Premium Discount Sale And Collection Of Finance Receivables And Cost Recovery Proceeds Net FinancingReceivableExcludingAccruedInterestUnamortizedLoanFeeCostAndPurchasePremiumDiscountSaleAndCollectionOfFinanceReceivablesAndCostRecoveryProceedsNet	53000000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576900000	usd
CY2024Q2	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	235447000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	61013000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	155105000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	12537000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	326137000	usd
CY2023Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	10454000	usd
CY2023Q1	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	336591000	usd
CY2023Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	27284000	usd
CY2023Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	363875000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Period Increase Decrease And Writeoff Net FinancingReceivableExcludingAccruedInterestPeriodIncreaseDecreaseAndWriteoffNet	142600000	usd
CY2024Q2	bxmt	Financing Receivable Number Of Impaired Loans Resolved During The Period FinancingReceivableNumberOfImpairedLoansResolvedDuringThePeriod	1	loan
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff	54048000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff	19502000	usd
CY2024Q1	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60200000	usd
CY2024Q2	bxmt	Building Acquired Through Foreclosure BuildingAcquiredThroughForeclosure	19379000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60203000	usd
CY2024Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	60018000	usd
	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	usd
CY2024Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2024Q2	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	bxmt	Financing Receivable Weighted Average Risk Rating FinancingReceivableWeightedAverageRiskRating	3.0
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	235447000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	61013000	usd
CY2024Q1	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	751370000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	155105000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	12537000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	326137000	usd
CY2023Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	10454000	usd
CY2023Q1	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	336591000	usd
CY2023Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	27284000	usd
CY2023Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	363875000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Period Increase Decrease And Writeoff Net FinancingReceivableExcludingAccruedInterestPeriodIncreaseDecreaseAndWriteoffNet	142600000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2024Q2	bxmt	Financing Receivable Number Of Impaired Loans Resolved During The Period FinancingReceivableNumberOfImpairedLoansResolvedDuringThePeriod	1	loan
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff	54048000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff	19502000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	73550000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2024	bxmt	Financing Receivable Modified Number Of Contracts FinancingReceivableModifiedNumberOfContracts	5	loan
CY2024Q1	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60200000	usd
CY2024Q2	bxmt	Land And Site Improvements Acquired Through Foreclosure LandAndSiteImprovementsAcquiredThroughForeclosure	40824000	usd
CY2024Q2	bxmt	Building Acquired Through Foreclosure BuildingAcquiredThroughForeclosure	19379000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60203000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Accumulated Depreciation RealEstateAcquiredThroughForeclosureAccumulatedDepreciation	185000	usd
CY2024Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	60018000	usd
	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	usd
CY2024Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2024Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	963000	usd
	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2023Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	0	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	235447000	usd
CY2024Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	61013000	usd
CY2024Q1	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	751370000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	155105000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	12537000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2022Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	326137000	usd
CY2023Q1	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	10454000	usd
CY2023Q2	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Period Increase Decrease FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossPeriodIncreaseDecrease	27284000	usd
CY2023Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	363875000	usd
CY2024Q2	bxmt	Financing Receivable Excluding Accrued Interest Period Increase Decrease And Writeoff Net FinancingReceivableExcludingAccruedInterestPeriodIncreaseDecreaseAndWriteoffNet	142600000	usd
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893900000	usd
CY2024Q2	bxmt	Financing Receivable Number Of Impaired Loans Resolved During The Period FinancingReceivableNumberOfImpairedLoansResolvedDuringThePeriod	1	loan
CY2024Q2	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	893938000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year One Originated Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearOneOriginatedCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Two Originated Fiscal Year Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearTwoOriginatedFiscalYearBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Three Originated Two Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearThreeOriginatedTwoYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Four Originated Three Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFourOriginatedThreeYearsBeforeCurrentFiscalYearWriteoff	54048000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Year Five Originated Four Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestYearFiveOriginatedFourYearsBeforeCurrentFiscalYearWriteoff	0	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Originated More Than Five Years Before Current Fiscal Year Writeoff FinancingReceivableExcludingAccruedInterestOriginatedMoreThanFiveYearsBeforeCurrentFiscalYearWriteoff	19502000	usd
	us-gaap	Financing Receivable Excluding Accrued Interest Allowance For Credit Loss Writeoff FinancingReceivableExcludingAccruedInterestAllowanceForCreditLossWriteoff	73550000	usd
CY2023Q4	us-gaap	Financing Receivable Allowance For Credit Loss Excluding Accrued Interest FinancingReceivableAllowanceForCreditLossExcludingAccruedInterest	576936000	usd
CY2024Q1	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60200000	usd
CY2024Q2	bxmt	Land And Site Improvements Acquired Through Foreclosure LandAndSiteImprovementsAcquiredThroughForeclosure	40824000	usd
CY2024Q2	bxmt	Building Acquired Through Foreclosure BuildingAcquiredThroughForeclosure	19379000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60203000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Accumulated Depreciation RealEstateAcquiredThroughForeclosureAccumulatedDepreciation	185000	usd
CY2024Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	60018000	usd
	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	usd
CY2024Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2024Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	963000	usd
	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2023Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	0	usd
CY2023Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	0	usd
CY2023Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	0	usd
CY2024Q2	bxmt	Building Acquired Through Foreclosure BuildingAcquiredThroughForeclosure	19379000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Gross RealEstateAcquiredThroughForeclosureGross	60203000	usd
CY2024Q2	bxmt	Real Estate Acquired Through Foreclosure Accumulated Depreciation RealEstateAcquiredThroughForeclosureAccumulatedDepreciation	185000	usd
CY2024Q2	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	60018000	usd
	us-gaap	Impairment Of Long Lived Assets Held For Use ImpairmentOfLongLivedAssetsHeldForUse	0	usd
CY2024Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2024Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	963000	usd
	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2023Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	0	usd
CY2023Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2023Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	0	usd
CY2024Q2	us-gaap	Interest Receivable InterestReceivable	196814000	usd
CY2023Q4	us-gaap	Interest Receivable InterestReceivable	214835000	usd
CY2024Q2	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	15904000	usd
CY2023Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	103500000	usd
CY2024Q2	bxmt	Accounts Receivable Net Current And Other Assets Current AccountsReceivableNetCurrentAndOtherAssetsCurrent	7549000	usd
CY2023Q4	bxmt	Accounts Receivable Net Current And Other Assets Current AccountsReceivableNetCurrentAndOtherAssetsCurrent	2420000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	650000	usd
CY2023Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	1020000	usd
CY2024Q2	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	0	usd
CY2023Q4	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	152423000	usd
CY2024Q2	us-gaap	Other Assets OtherAssets	225795000	usd
CY2023Q4	us-gaap	Other Assets OtherAssets	476088000	usd
CY2024Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	963000	usd
	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Depreciation Expenses RealEstateOwnedDepreciationExpenses	185000	usd
CY2024Q2	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Operating Expenses RealEstateOwnedOperatingExpenses	778000	usd
	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2023Q2	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	0	usd
CY2023Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
CY2023Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	0	usd
CY2024Q2	us-gaap	Interest Receivable InterestReceivable	196814000	usd
CY2023Q4	us-gaap	Interest Receivable InterestReceivable	214835000	usd
CY2024Q2	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	15904000	usd
CY2023Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	103500000	usd
CY2024Q2	bxmt	Accounts Receivable Net Current And Other Assets Current AccountsReceivableNetCurrentAndOtherAssetsCurrent	7549000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	650000	usd
CY2023Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	1020000	usd
CY2024Q2	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	0	usd
CY2023Q4	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	152423000	usd
CY2023Q4	us-gaap	Other Assets OtherAssets	476088000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107390000	usd
CY2024Q2	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	90223000	usd
CY2023Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	97820000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	18726000	usd
CY2023Q4	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	26342000	usd
CY2023Q2	bxmt	Real Estate Owned Income RealEstateOwnedIncome	0	usd
	bxmt	Real Estate Owned Expenses RealEstateOwnedExpenses	0	usd
CY2023Q4	us-gaap	Real Estate Acquired Through Foreclosure RealEstateAcquiredThroughForeclosure	0	usd
CY2024Q2	us-gaap	Interest Receivable InterestReceivable	196814000	usd
CY2023Q4	us-gaap	Interest Receivable InterestReceivable	214835000	usd
CY2024Q2	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	15904000	usd
CY2023Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	103500000	usd
CY2024Q2	bxmt	Accounts Receivable Net Current And Other Assets Current AccountsReceivableNetCurrentAndOtherAssetsCurrent	7549000	usd
CY2023Q4	bxmt	Accounts Receivable Net Current And Other Assets Current AccountsReceivableNetCurrentAndOtherAssetsCurrent	2420000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2024Q2	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	650000	usd
CY2023Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	1020000	usd
CY2024Q2	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	0	usd
CY2023Q4	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	152423000	usd
CY2024Q2	us-gaap	Other Assets OtherAssets	225795000	usd
CY2023Q4	us-gaap	Other Assets OtherAssets	476088000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107390000	usd
CY2024Q2	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	90223000	usd
CY2023Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	97820000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2024Q2	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	18726000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9946000	usd
CY2023Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	15371000	usd
CY2024Q2	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	6365000	usd
CY2023Q4	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	7265000	usd
CY2024Q2	bxmt	Secured Debt Repayments Pending Servicer Remittance SecuredDebtRepaymentsPendingServicerRemittance	0	usd
CY2023Q4	bxmt	Secured Debt Repayments Pending Servicer Remittance SecuredDebtRepaymentsPendingServicerRemittance	13526000	usd
CY2024Q2	us-gaap	Other Liabilities OtherLiabilities	257299000	usd
CY2024Q2	us-gaap	Interest Receivable InterestReceivable	196814000	usd
CY2023Q4	us-gaap	Interest Receivable InterestReceivable	214835000	usd
CY2024Q2	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	15904000	usd
CY2023Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	103500000	usd
CY2024Q2	bxmt	Accounts Receivable Net Current And Other Assets Current AccountsReceivableNetCurrentAndOtherAssetsCurrent	7549000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	650000	usd
CY2023Q4	us-gaap	Prepaid Expense Current And Noncurrent PrepaidExpenseCurrentAndNoncurrent	1020000	usd
CY2024Q2	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	0	usd
CY2023Q4	bxmt	Loan Portfolio Payments Held By Our Third Party Loan Servicer LoanPortfolioPaymentsHeldByOurThirdPartyLoanServicer	152423000	usd
CY2023Q4	us-gaap	Other Assets OtherAssets	476088000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107390000	usd
CY2024Q2	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	90223000	usd
CY2023Q4	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	97820000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2024Q2	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	18726000	usd
CY2023Q4	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	26342000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9946000	usd
CY2023Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	15371000	usd
CY2024Q2	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	6365000	usd
CY2023Q4	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	7265000	usd
CY2024Q2	bxmt	Secured Debt Repayments Pending Servicer Remittance SecuredDebtRepaymentsPendingServicerRemittance	0	usd
CY2023Q4	bxmt	Secured Debt Repayments Pending Servicer Remittance SecuredDebtRepaymentsPendingServicerRemittance	13526000	usd
CY2024Q2	us-gaap	Other Liabilities OtherLiabilities	257299000	usd
CY2023Q4	us-gaap	Other Liabilities OtherLiabilities	362531000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	2700000	usd
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	5400000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9900000	usd
CY2024Q2	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107644000	usd
CY2023Q4	us-gaap	Dividends Payable Current And Noncurrent DividendsPayableCurrentAndNoncurrent	107390000	usd
CY2024Q2	us-gaap	Interest Payable Current And Noncurrent InterestPayableCurrentAndNoncurrent	90223000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	18726000	usd
CY2023Q4	bxmt	Management And Incentive Fee Payable ManagementAndIncentiveFeePayable	26342000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9946000	usd
CY2023Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	15371000	usd
CY2023Q4	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	7265000	usd
CY2024Q2	bxmt	Secured Debt Repayments Pending Servicer Remittance SecuredDebtRepaymentsPendingServicerRemittance	0	usd
CY2024Q2	us-gaap	Other Liabilities OtherLiabilities	257299000	usd
CY2023Q4	us-gaap	Other Liabilities OtherLiabilities	362531000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	2700000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9900000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-523000	usd
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	108000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	16300000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	428151000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	427701000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q4	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	697565000	usd
CY2023Q4	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	694386000	usd
CY2024Q1	us-gaap	Share Price SharePrice	17.42
	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	545000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	-3032000	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	42709000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	1074000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	420000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9946000	usd
CY2023Q4	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	15371000	usd
CY2024Q2	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	6365000	usd
CY2023Q4	us-gaap	Accounts Payable And Other Accrued Liabilities AccountsPayableAndOtherAccruedLiabilities	7265000	usd
CY2024Q2	bxmt	Secured Debt Repayments Pending Servicer Remittance SecuredDebtRepaymentsPendingServicerRemittance	0	usd
CY2024Q2	us-gaap	Other Liabilities OtherLiabilities	257299000	usd
CY2023Q4	us-gaap	Other Liabilities OtherLiabilities	362531000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	2700000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9900000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-523000	usd
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	108000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	16300000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	428151000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	427701000	usd
	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	545000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	-3032000	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	42709000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	242000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	1074000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	420000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	-2790000	usd
	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	43783000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	420000	usd
	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	339400000	usd
CY2023Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	103500000	usd
CY2024Q2	bxmt	Common And Preferred Stock Shares Authorized CommonAndPreferredStockSharesAuthorized	500000000	shares
CY2024Q2	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	400000000	shares
CY2024Q2	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	100000000	shares
CY2023Q4	us-gaap	Other Liabilities OtherLiabilities	362531000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	2700000	usd
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	5400000	usd
CY2024Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	9900000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-523000	usd
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	108000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	16300000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	428151000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	427701000	usd
CY2023Q4	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	337721000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q4	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	697565000	usd
CY2023Q4	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	694386000	usd
CY2024Q1	us-gaap	Share Price SharePrice	17.42
	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	545000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	-3032000	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	42709000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	242000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	1074000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	420000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	-2790000	usd
	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	43783000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	420000	usd
	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	339400000	usd
CY2023Q4	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	103500000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	-523000	usd
	us-gaap	Off Balance Sheet Credit Loss Liability Credit Loss Expense Reversal OffBalanceSheetCreditLossLiabilityCreditLossExpenseReversal	108000	usd
CY2023Q2	us-gaap	Off Balance Sheet Credit Loss Liability OffBalanceSheetCreditLossLiability	16300000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	428151000	usd
CY2024Q2	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	427701000	usd
CY2023Q4	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	337721000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q4	bxmt	Loan Participations Sold Total Loan LoanParticipationsSoldTotalLoan	697565000	usd
CY2023Q4	bxmt	Loan Participations Sold Total Loan Amount LoanParticipationsSoldTotalLoanAmount	694386000	usd
CY2024Q1	us-gaap	Share Price SharePrice	17.42
	us-gaap	Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months CashFlowHedgeGainLossToBeReclassifiedWithinTwelveMonths	545000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	-3032000	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossBeforeReclassificationAndTax	42709000	usd
	us-gaap	Other Comprehensive Income Loss Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossNetInvestmentHedgeGainLossReclassificationBeforeTax	0	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	242000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossBeforeReclassificationAndTax	1074000	usd
CY2024Q2	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	420000	usd
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	-2790000	usd
	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	43783000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	420000	usd
	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	339400000	usd
	us-gaap	Interest Expense Operating InterestExpenseOperating	683100000	usd
CY2024Q2	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	15900000	usd
CY2024Q2	bxmt	Common And Preferred Stock Shares Authorized CommonAndPreferredStockSharesAuthorized	500000000	shares
CY2024Q2	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	400000000	shares
CY2024Q2	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	100000000	shares
	us-gaap	Other Comprehensive Income Loss Cash Flow Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowHedgeGainLossReclassificationBeforeTax	845000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	-2790000	usd
	bxmt	Other Comprehensive Income Loss Net Investment Hedge And Cash Flow Hedge Gain Loss Before Reclassification And Tax OtherComprehensiveIncomeLossNetInvestmentHedgeAndCashFlowHedgeGainLossBeforeReclassificationAndTax	43783000	usd
CY2024Q2	bxmt	Other Comprehensive Income Loss Cash Flow And Net Investment Hedge Gain Loss Reclassification Before Tax OtherComprehensiveIncomeLossCashFlowAndNetInvestmentHedgeGainLossReclassificationBeforeTax	420000	usd
CY2024Q2	us-gaap	Interest Expense Operating InterestExpenseOperating	339400000	usd
	us-gaap	Interest Expense Operating InterestExpenseOperating	683100000	usd
CY2024Q2	us-gaap	Collateral Already Posted Aggregate Fair Value CollateralAlreadyPostedAggregateFairValue	15900000	usd
CY2024Q2	bxmt	Common And Preferred Stock Shares Authorized CommonAndPreferredStockSharesAuthorized	500000000	shares
CY2024Q2	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	400000000	shares
CY2024Q2	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	100000000	shares
CY2023Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2023Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2023Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	173569397	shares
CY2022Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172106593	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	29649	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	34126	shares
CY2024Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	174008611	shares
CY2023Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172649764	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Forfeited StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited	97985	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Shares Authorized DividendReinvestmentAndDirectStockPurchasePlanSharesAuthorized	10000000	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	3613	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Remaining Shares Available For Future Issuance DividendReinvestmentAndDirectStockPurchasePlanRemainingSharesAvailableForFutureIssuance	9971796	shares
	bxmt	Sale Of Stock Number Of Equity Distribution Agreements SaleOfStockNumberOfEquityDistributionAgreements	7	agreement
	bxmt	Sale Of Stock Maximum Authorized Amount SaleOfStockMaximumAuthorizedAmount	699100000	usd
	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	0	shares
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
CY2024Q2	us-gaap	Dividends Common Stock DividendsCommonStock	107644000	usd
CY2024Q2	bxmt	Common And Preferred Stock Shares Authorized CommonAndPreferredStockSharesAuthorized	500000000	shares
CY2024Q2	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	400000000	shares
CY2024Q2	us-gaap	Preferred Stock Shares Authorized PreferredStockSharesAuthorized	100000000	shares
CY2023Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2023Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2023Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	173569397	shares
CY2022Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172106593	shares
	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	3613	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	29649	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	34126	shares
CY2024Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	174008611	shares
CY2023Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172649764	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Forfeited StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited	97985	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Forfeited StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited	0	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Shares Authorized DividendReinvestmentAndDirectStockPurchasePlanSharesAuthorized	10000000	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	3613	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Remaining Shares Available For Future Issuance DividendReinvestmentAndDirectStockPurchasePlanRemainingSharesAvailableForFutureIssuance	9971796	shares
	bxmt	Sale Of Stock Number Of Equity Distribution Agreements SaleOfStockNumberOfEquityDistributionAgreements	7	agreement
	bxmt	Sale Of Stock Maximum Authorized Amount SaleOfStockMaximumAuthorizedAmount	699100000	usd
	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	0	shares
	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	0	shares
CY2024Q2	bxmt	Sale Of Stock Remaining Authorized Amount SaleOfStockRemainingAuthorizedAmount	480900000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Dividends Common Stock DividendsCommonStock	107600000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
CY2024Q2	us-gaap	Dividends Common Stock DividendsCommonStock	107644000	usd
	us-gaap	Dividends Common Stock DividendsCommonStock	215322000	usd
CY2023Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2023Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2023Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	173569397	shares
CY2022Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172106593	shares
	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	3613	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	34126	shares
CY2024Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	174008611	shares
CY2023Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172649764	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Forfeited StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited	97985	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Shares Authorized DividendReinvestmentAndDirectStockPurchasePlanSharesAuthorized	10000000	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	3613	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Remaining Shares Available For Future Issuance DividendReinvestmentAndDirectStockPurchasePlanRemainingSharesAvailableForFutureIssuance	9971796	shares
	bxmt	Sale Of Stock Number Of Equity Distribution Agreements SaleOfStockNumberOfEquityDistributionAgreements	7	agreement
	bxmt	Sale Of Stock Maximum Authorized Amount SaleOfStockMaximumAuthorizedAmount	699100000	usd
	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	0	shares
	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	0	shares
CY2024Q2	bxmt	Sale Of Stock Remaining Authorized Amount SaleOfStockRemainingAuthorizedAmount	480900000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Dividends Common Stock DividendsCommonStock	107600000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
CY2023Q2	us-gaap	Dividends Common Stock DividendsCommonStock	106832000	usd
CY2023Q2	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	196000	usd
CY2024Q2	us-gaap	Dividends Dividends	107873000	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
CY2023Q4	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2023Q4	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Outstanding PreferredStockSharesOutstanding	0	shares
CY2024Q2	us-gaap	Preferred Stock Shares Issued PreferredStockSharesIssued	0	shares
CY2023Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	173569397	shares
CY2022Q4	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172106593	shares
	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	3165	shares
	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	3613	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	406400	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Net Of Forfeitures StockIssuedDuringPeriodSharesRestrictedStockAwardNetOfForfeitures	505432	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	29649	shares
	bxmt	Stock Issued During Period Shares Deferred Stock Units StockIssuedDuringPeriodSharesDeferredStockUnits	34126	shares
CY2024Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	174008611	shares
CY2023Q2	bxmt	Common Stock Shares Outstanding Including Deferred Stock Units CommonStockSharesOutstandingIncludingDeferredStockUnits	172649764	shares
	us-gaap	Stock Issued During Period Shares Restricted Stock Award Forfeited StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited	0	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Shares Authorized DividendReinvestmentAndDirectStockPurchasePlanSharesAuthorized	10000000	shares
	us-gaap	Stock Issued During Period Shares Dividend Reinvestment Plan StockIssuedDuringPeriodSharesDividendReinvestmentPlan	3165	shares
CY2024Q2	bxmt	Dividend Reinvestment And Direct Stock Purchase Plan Remaining Shares Available For Future Issuance DividendReinvestmentAndDirectStockPurchasePlanRemainingSharesAvailableForFutureIssuance	9971796	shares
	bxmt	Sale Of Stock Number Of Equity Distribution Agreements SaleOfStockNumberOfEquityDistributionAgreements	7	agreement
	bxmt	Sale Of Stock Maximum Authorized Amount SaleOfStockMaximumAuthorizedAmount	699100000	usd
	us-gaap	Sale Of Stock Number Of Shares Issued In Transaction SaleOfStockNumberOfSharesIssuedInTransaction	0	shares
CY2024Q2	bxmt	Sale Of Stock Remaining Authorized Amount SaleOfStockRemainingAuthorizedAmount	480900000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2024Q2	us-gaap	Dividends Common Stock DividendsCommonStock	107600000	usd
CY2024Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
CY2023Q2	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	0.62
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.24
CY2024Q2	us-gaap	Dividends Common Stock DividendsCommonStock	107644000	usd
CY2023Q2	us-gaap	Dividends Common Stock DividendsCommonStock	106832000	usd
	us-gaap	Dividends Common Stock DividendsCommonStock	215322000	usd
	us-gaap	Dividends Common Stock DividendsCommonStock	213648000	usd
CY2024Q2	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	229000	usd
CY2023Q2	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	196000	usd
	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	452000	usd
CY2023Q2	us-gaap	Dividends Dividends	107028000	usd
	us-gaap	Dividends Dividends	215774000	usd
	us-gaap	Dividends Dividends	214100000	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2024Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
CY2023Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	3556000	usd
	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	7111000	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	105207000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	226519000	usd
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180877974	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
CY2024Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-216500000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	9500000	usd
CY2023Q4	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	183900000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-174400000	usd
	us-gaap	Dividends Common Stock DividendsCommonStock	215322000	usd
CY2024Q2	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	229000	usd
	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	452000	usd
	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	452000	usd
CY2024Q2	us-gaap	Dividends Dividends	107873000	usd
	us-gaap	Dividends Dividends	214100000	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2024Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
CY2023Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	3556000	usd
	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	105207000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	226519000	usd
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180877974	shares
CY2024Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.35
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	10300000	usd
CY2024Q2	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	226800000	usd
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-216500000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	9500000	usd
CY2023Q4	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	183900000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-174400000	usd
	us-gaap	Management And Service Fees Rate ManagementAndServiceFeesRate	0.0150
	us-gaap	Management And Service Fees Incentive Rate ManagementAndServiceFeesIncentiveRate	0.20
CY2024Q2	bxmt	Management Fee Core Earnings Fee Percentage ManagementFeeCoreEarningsFeePercentage	0.0700
	bxmt	Management Fee Core Earnings Measurement Period ManagementFeeCoreEarningsMeasurementPeriod	P3Y
	bxmt	Management Fee Core Earnings Minimum Threshold ManagementFeeCoreEarningsMinimumThreshold	0
CY2023Q4	bxmt	Accrued Management And Incentive Fees Payable AccruedManagementAndIncentiveFeesPayable	26300000	usd
	us-gaap	Dividends Common Stock DividendsCommonStock	213648000	usd
CY2023Q2	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	196000	usd
	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	452000	usd
	us-gaap	Dividends Share Based Compensation DividendsShareBasedCompensation	452000	usd
	us-gaap	Dividends Dividends	215774000	usd
	us-gaap	Dividends Dividends	214100000	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.59
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2024Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-61057000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	226519000	usd
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180877974	shares
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
CY2024Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	10300000	usd
CY2024Q2	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	226800000	usd
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-216500000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	9500000	usd
CY2023Q4	us-gaap	Aoci Loss Cash Flow Hedge Cumulative Gain Loss After Tax AociLossCashFlowHedgeCumulativeGainLossAfterTax	183900000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-174400000	usd
	us-gaap	Management And Service Fees Rate ManagementAndServiceFeesRate	0.0150
	bxmt	Management Fee Core Earnings Measurement Period ManagementFeeCoreEarningsMeasurementPeriod	P3Y
	bxmt	Management Fee Core Earnings Minimum Threshold ManagementFeeCoreEarningsMinimumThreshold	0
CY2024Q2	bxmt	Accrued Management And Incentive Fees Payable AccruedManagementAndIncentiveFeesPayable	18700000	usd
CY2023Q4	bxmt	Accrued Management And Incentive Fees Payable AccruedManagementAndIncentiveFeesPayable	26300000	usd
CY2024Q2	us-gaap	Professional Fees ProfessionalFees	3817000	usd
CY2023Q2	us-gaap	Professional Fees ProfessionalFees	3291000	usd
	us-gaap	Professional Fees ProfessionalFees	6570000	usd
CY2024Q2	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	1881000	usd
CY2023Q2	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	2066000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-0.35
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	-1.06
	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.27
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	101651000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	-184895000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	219408000	usd
CY2024Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
CY2023Q2	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	3556000	usd
	us-gaap	Interest On Convertible Debt Net Of Tax InterestOnConvertibleDebtNetOfTax	0	usd
CY2024Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-61057000	usd
CY2023Q2	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	105207000	usd
	us-gaap	Net Income Loss Available To Common Stockholders Diluted NetIncomeLossAvailableToCommonStockholdersDiluted	-184895000	usd
CY2024Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	173967340	shares
	us-gaap	Professional Fees ProfessionalFees	7957000	usd
	us-gaap	Professional Fees ProfessionalFees	6570000	usd
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172615385	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	174004464	shares
	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	172606914	shares
CY2024Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8271060	shares
CY2024Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	173967340	shares
CY2023Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180886445	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	174004464	shares
	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	180877974	shares
CY2024Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-0.35
CY2023Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.58
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	-1.06
	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.25
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	0	shares
	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2023Q2	us-gaap	Incremental Common Shares Attributable To Conversion Of Debt Securities IncrementalCommonSharesAttributableToConversionOfDebtSecurities	8300000	shares
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	10300000	usd
CY2024Q2	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-216500000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	9500000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Foreign Currency Translation Adjustment Net Of Tax AccumulatedOtherComprehensiveIncomeLossForeignCurrencyTranslationAdjustmentNetOfTax	-174400000	usd
	us-gaap	Management And Service Fees Rate ManagementAndServiceFeesRate	0.0150
	bxmt	Management Fee Core Earnings Measurement Period ManagementFeeCoreEarningsMeasurementPeriod	P3Y
	bxmt	Management Fee Core Earnings Minimum Threshold ManagementFeeCoreEarningsMinimumThreshold	0
CY2024Q2	bxmt	Accrued Management And Incentive Fees Payable AccruedManagementAndIncentiveFeesPayable	18700000	usd
CY2023Q4	bxmt	Accrued Management And Incentive Fees Payable AccruedManagementAndIncentiveFeesPayable	26300000	usd
CY2024Q2	us-gaap	Professional Fees ProfessionalFees	3817000	usd
CY2023Q2	us-gaap	Professional Fees ProfessionalFees	3291000	usd
CY2024Q2	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	1881000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3357000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3997000	usd
CY2024Q2	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	5698000	usd
	us-gaap	Management And Service Fees Rate ManagementAndServiceFeesRate	0.0150
	us-gaap	Management And Service Fees Incentive Rate ManagementAndServiceFeesIncentiveRate	0.20
CY2024Q2	bxmt	Management Fee Core Earnings Fee Percentage ManagementFeeCoreEarningsFeePercentage	0.0700
	bxmt	Management Fee Core Earnings Measurement Period ManagementFeeCoreEarningsMeasurementPeriod	P3Y
	bxmt	Management Fee Core Earnings Minimum Threshold ManagementFeeCoreEarningsMinimumThreshold	0
CY2023Q4	bxmt	Accrued Management And Incentive Fees Payable AccruedManagementAndIncentiveFeesPayable	26300000	usd
CY2024Q2	us-gaap	Professional Fees ProfessionalFees	3817000	usd
CY2023Q2	us-gaap	Professional Fees ProfessionalFees	3291000	usd
	us-gaap	Professional Fees ProfessionalFees	7957000	usd
	us-gaap	Professional Fees ProfessionalFees	6570000	usd
CY2023Q2	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	2066000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3357000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3997000	usd
CY2024Q2	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	5698000	usd
CY2023Q2	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	5357000	usd
	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	11314000	usd
CY2024Q2	us-gaap	Restricted Stock Expense RestrictedStockExpense	7761000	usd
CY2023Q2	us-gaap	Restricted Stock Expense RestrictedStockExpense	7492000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	15672000	usd
CY2024Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	201000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	402000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	336000	usd
CY2024Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7962000	usd
CY2023Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7665000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	16074000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	15320000	usd
CY2024Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13660000	usd
CY2023Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13022000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	27388000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	25887000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3100000	usd
CY2013Q2	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	25875000	shares
CY2013Q2	bxmt	Operating Loss Carryforwards Limitations On Use Annual Limitation OperatingLossCarryforwardsLimitationsOnUseAnnualLimitation	2000000.0	usd
CY2024Q2	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	159000000.0	usd
CY2024Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	2	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	9	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Retired Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfRetiredStockIncentivePlans	7	plan
CY2024Q2	us-gaap	Professional Fees ProfessionalFees	3817000	usd
CY2023Q2	us-gaap	Professional Fees ProfessionalFees	3291000	usd
	us-gaap	Professional Fees ProfessionalFees	6570000	usd
CY2024Q2	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	1881000	usd
CY2023Q2	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	2066000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3357000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3997000	usd
CY2024Q2	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	5698000	usd
	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	11314000	usd
CY2024Q2	us-gaap	Restricted Stock Expense RestrictedStockExpense	7761000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	15672000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	14984000	usd
CY2024Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	201000	usd
CY2023Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	173000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	402000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	336000	usd
CY2024Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7962000	usd
CY2023Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7665000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	16074000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	15320000	usd
CY2024Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13660000	usd
CY2023Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13022000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	25887000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2200000	usd
CY2023Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1200000	usd
CY2013Q2	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	25875000	shares
CY2013Q2	bxmt	Operating Loss Carryforwards Limitations On Use Annual Limitation OperatingLossCarryforwardsLimitationsOnUseAnnualLimitation	2000000.0	usd
CY2024Q2	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	159000000.0	usd
CY2024Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	2	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	9	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Retired Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfRetiredStockIncentivePlans	7	plan
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3357000	usd
	us-gaap	Other General And Administrative Expense OtherGeneralAndAdministrativeExpense	3997000	usd
CY2024Q2	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	5698000	usd
	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	10567000	usd
CY2024Q2	us-gaap	Restricted Stock Expense RestrictedStockExpense	7761000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	15672000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	14984000	usd
CY2024Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	201000	usd
CY2023Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	173000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	402000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	336000	usd
CY2024Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7962000	usd
CY2023Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7665000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	16074000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	15320000	usd
CY2024Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13660000	usd
CY2023Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13022000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	27388000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	25887000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3100000	usd
CY2013Q2	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	25875000	shares
CY2013Q2	bxmt	Operating Loss Carryforwards Limitations On Use Annual Limitation OperatingLossCarryforwardsLimitationsOnUseAnnualLimitation	2000000.0	usd
CY2024Q2	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	159000000.0	usd
CY2024Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	2	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	9	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Retired Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfRetiredStockIncentivePlans	7	plan
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	373876000	usd
CY2023Q4	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	350014000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	350014000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	23015737000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Fair Value LoanParticipationsSoldLiabilitiesFairValue	100098000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q2	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	5357000	usd
	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	11314000	usd
	bxmt	General And Administrative Expense Excluding Non Cash Compensation Expense GeneralAndAdministrativeExpenseExcludingNonCashCompensationExpense	10567000	usd
CY2024Q2	us-gaap	Restricted Stock Expense RestrictedStockExpense	7761000	usd
CY2023Q2	us-gaap	Restricted Stock Expense RestrictedStockExpense	7492000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	15672000	usd
	us-gaap	Restricted Stock Expense RestrictedStockExpense	14984000	usd
CY2024Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	201000	usd
CY2023Q2	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	173000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	402000	usd
	bxmt	Director Share Based Payment Arrangement Expense DirectorShareBasedPaymentArrangementExpense	336000	usd
CY2024Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7962000	usd
CY2023Q2	us-gaap	Share Based Compensation ShareBasedCompensation	7665000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	16074000	usd
	us-gaap	Share Based Compensation ShareBasedCompensation	15320000	usd
CY2023Q2	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	13022000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	27388000	usd
	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	25887000	usd
CY2024Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	1200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	2200000	usd
	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	3100000	usd
CY2013Q2	us-gaap	Stock Issued During Period Shares New Issues StockIssuedDuringPeriodSharesNewIssues	25875000	shares
CY2013Q2	bxmt	Operating Loss Carryforwards Limitations On Use Annual Limitation OperatingLossCarryforwardsLimitationsOnUseAnnualLimitation	2000000.0	usd
CY2024Q2	us-gaap	Operating Loss Carryforwards OperatingLossCarryforwards	159000000.0	usd
CY2024Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	2	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfStockIncentivePlans	9	plan
CY2022Q2	bxmt	Share Based Compensation Arrangement By Share Based Payment Award Number Of Retired Stock Incentive Plans ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfRetiredStockIncentivePlans	7	plan
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	373876000	usd
CY2024Q2	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	373876000	usd
CY2024Q2	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	373876000	usd
CY2023Q4	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	350014000	usd
CY2023Q4	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	350014000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	350014000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	23015737000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	us-gaap	Derivative Assets DerivativeAssets	4878000	usd
CY2023Q4	us-gaap	Derivative Assets DerivativeAssets	1890000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2023Q4	us-gaap	Derivative Liabilities DerivativeLiabilities	94817000	usd
CY2024Q2	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	373876000	usd
CY2024Q2	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	373876000	usd
CY2024Q2	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	373876000	usd
CY2023Q4	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	350014000	usd
CY2023Q4	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	350014000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	350014000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23010660000	usd
CY2024Q2	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	21872283000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	23015737000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Fair Value LoanParticipationsSoldLiabilitiesFairValue	100098000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q4	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	337721000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Fair Value LoanParticipationsSoldLiabilitiesFairValue	333745000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal Remainder Of Fiscal Year LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear	2001553000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	2431633000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	3872332000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	525268000	usd
CY2024Q2	bxmt	Long Term Debt Maturity After Year Four LongTermDebtMaturityAfterYearFour	1768697000	usd
CY2024Q2	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	16000571000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	us-gaap	Derivative Liabilities DerivativeLiabilities	24395000	usd
CY2024Q2	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	373876000	usd
CY2024Q2	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	373876000	usd
CY2023Q4	bxmt	Cash And Cash Equivalents CashAndCashEquivalents	350014000	usd
CY2023Q4	us-gaap	Cash And Cash Equivalents Fair Value Disclosure CashAndCashEquivalentsFairValueDisclosure	350014000	usd
CY2024Q2	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	21976910000	usd
CY2024Q2	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	21872283000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest After Allowance For Credit Loss FinancingReceivableExcludingAccruedInterestAfterAllowanceForCreditLoss	23210076000	usd
CY2023Q4	us-gaap	Financing Receivable Excluding Accrued Interest Before Allowance For Credit Loss Fee And Loan In Process FinancingReceivableExcludingAccruedInterestBeforeAllowanceForCreditLossFeeAndLoanInProcess	23923719000	usd
CY2023Q4	us-gaap	Loans Receivable Fair Value Disclosure LoansReceivableFairValueDisclosure	23015737000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	100442000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Fair Value LoanParticipationsSoldLiabilitiesFairValue	100098000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q4	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	337721000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal Remainder Of Fiscal Year LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear	2001553000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	5401088000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	3872332000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	525268000	usd
CY2024Q2	bxmt	Long Term Debt Maturity After Year Four LongTermDebtMaturityAfterYearFour	1768697000	usd
CY2024Q2	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	16000571000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100600000	usd
	bxmt	Board Of Directors Number Of Members BoardOfDirectorsNumberOfMembers	9	director
	bxmt	Board Of Directors Number Of Directors Eligible For Compensation BoardOfDirectorsNumberOfDirectorsEligibleForCompensation	7	director
	bxmt	Board Of Directors Number Of Members Not Eligible For Annual Compensation BoardOfDirectorsNumberOfMembersNotEligibleForAnnualCompensation	2	director
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100580000	usd
CY2024Q2	bxmt	Loan Participations Sold Liabilities Fair Value LoanParticipationsSoldLiabilitiesFairValue	100098000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Amount LoanParticipationsSoldLiabilitiesAmount	337179000	usd
CY2023Q4	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	337721000	usd
CY2023Q4	bxmt	Loan Participations Sold Liabilities Fair Value LoanParticipationsSoldLiabilitiesFairValue	333745000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal Remainder Of Fiscal Year LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear	2001553000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	2431633000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Two LongTermDebtMaturitiesRepaymentsOfPrincipalInYearTwo	5401088000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	3872332000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	525268000	usd
CY2024Q2	bxmt	Long Term Debt Maturity After Year Four LongTermDebtMaturityAfterYearFour	1768697000	usd
CY2024Q2	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	16000571000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100600000	usd
	bxmt	Board Of Directors Number Of Members BoardOfDirectorsNumberOfMembers	9	director
	bxmt	Board Of Directors Number Of Directors Eligible For Compensation BoardOfDirectorsNumberOfDirectorsEligibleForCompensation	7	director
	bxmt	Board Of Directors Number Of Members Not Eligible For Annual Compensation BoardOfDirectorsNumberOfMembersNotEligibleForAnnualCompensation	2	director
CY2023Q4	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	337721000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal Remainder Of Fiscal Year LongTermDebtMaturitiesRepaymentsOfPrincipalRemainderOfFiscalYear	2001553000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Next Twelve Months LongTermDebtMaturitiesRepaymentsOfPrincipalInNextTwelveMonths	2431633000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Three LongTermDebtMaturitiesRepaymentsOfPrincipalInYearThree	3872332000	usd
CY2024Q2	us-gaap	Long Term Debt Maturities Repayments Of Principal In Year Four LongTermDebtMaturitiesRepaymentsOfPrincipalInYearFour	525268000	usd
CY2024Q2	bxmt	Long Term Debt Maturity After Year Four LongTermDebtMaturityAfterYearFour	1768697000	usd
CY2024Q2	us-gaap	Debt Instrument Carrying Amount DebtInstrumentCarryingAmount	16000571000	usd
CY2024Q2	bxmt	Loan Exposure Amount Including Non Consolidated Senior Interests LoanExposureAmountIncludingNonConsolidatedSeniorInterests	725400000	usd
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100600000	usd
	bxmt	Board Of Directors Number Of Members BoardOfDirectorsNumberOfMembers	9	director
	bxmt	Board Of Directors Number Of Directors Eligible For Compensation BoardOfDirectorsNumberOfDirectorsEligibleForCompensation	7	director
	bxmt	Board Of Directors Number Of Members Not Eligible For Annual Compensation BoardOfDirectorsNumberOfMembersNotEligibleForAnnualCompensation	2	director
CY2024Q2	bxmt	Loan Participation Liabilities Principal Amount LoanParticipationLiabilitiesPrincipalAmount	100600000	usd
	bxmt	Board Of Directors Number Of Members BoardOfDirectorsNumberOfMembers	9	director
	bxmt	Board Of Directors Number Of Directors Eligible For Compensation BoardOfDirectorsNumberOfDirectorsEligibleForCompensation	7	director
	bxmt	Board Of Directors Number Of Members Not Eligible For Annual Compensation BoardOfDirectorsNumberOfMembersNotEligibleForAnnualCompensation	2	director

Files In Submission

Name	View Source	Status
0001061630-24-000116-index-headers.html	Edgar Link	pending
0001061630-24-000116-index.html	Edgar Link	pending
0001061630-24-000116.txt	Edgar Link	pending
0001061630-24-000116-xbrl.zip	Edgar Link	pending
bxmt-20240630.htm	Edgar Link	pending
bxmt-20240630.xsd	Edgar Link	pending
bxmt-20240630_g1.gif	Edgar Link	pending
bxmt-20240630_g2.jpg	Edgar Link	pending
bxmt-20240630_g3.jpg	Edgar Link	pending
exhibit1012q24.htm	Edgar Link	pending
exhibit1022q24.htm	Edgar Link	pending
exhibit3112q24.htm	Edgar Link	pending
exhibit3122q24.htm	Edgar Link	pending
exhibit3212q24.htm	Edgar Link	pending
exhibit3222q24.htm	Edgar Link	pending
exhibit9912q24.htm	Edgar Link	pending
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
bxmt-20240630_cal.xml	Edgar Link	unprocessable
bxmt-20240630_lab.xml	Edgar Link	unprocessable
bxmt-20240630_def.xml	Edgar Link	unprocessable
FilingSummary.xml	Edgar Link	unprocessable
bxmt-20240630_pre.xml	Edgar Link	unprocessable
bxmt-20240630_htm.xml	Edgar Link	completed
0001061630-24-000116-index-headers.html	Edgar Link	pending
0001061630-24-000116-index.html	Edgar Link	pending
0001061630-24-000116.txt	Edgar Link	pending
0001061630-24-000116-xbrl.zip	Edgar Link	pending
bxmt-20240630.htm	Edgar Link	pending
bxmt-20240630.xsd	Edgar Link	pending
bxmt-20240630_g1.gif	Edgar Link	pending
bxmt-20240630_g2.jpg	Edgar Link	pending
bxmt-20240630_g3.jpg	Edgar Link	pending
exhibit1012q24.htm	Edgar Link	pending
exhibit1022q24.htm	Edgar Link	pending
bxmt-20240630_cal.xml	Edgar Link	unprocessable
bxmt-20240630_def.xml	Edgar Link	unprocessable
bxmt-20240630_pre.xml	Edgar Link	unprocessable
bxmt-20240630_lab.xml	Edgar Link	unprocessable
bxmt-20240630_htm.xml	Edgar Link	completed
R100.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
exhibit3112q24.htm	Edgar Link	pending
exhibit3122q24.htm	Edgar Link	pending
exhibit3212q24.htm	Edgar Link	pending
exhibit3222q24.htm	Edgar Link	pending
exhibit9912q24.htm	Edgar Link	pending
Financial_Report.xlsx	Edgar Link	pending
MetaLinks.json	Edgar Link	pending
R1.htm	Edgar Link	pending
R10.htm	Edgar Link	pending
R100.htm	Edgar Link	pending
R11.htm	Edgar Link	pending
R12.htm	Edgar Link	pending
R13.htm	Edgar Link	pending
R14.htm	Edgar Link	pending
R15.htm	Edgar Link	pending
R16.htm	Edgar Link	pending
R17.htm	Edgar Link	pending
R18.htm	Edgar Link	pending
R19.htm	Edgar Link	pending
R2.htm	Edgar Link	pending
R20.htm	Edgar Link	pending
R21.htm	Edgar Link	pending
R22.htm	Edgar Link	pending
R23.htm	Edgar Link	pending
R24.htm	Edgar Link	pending
R25.htm	Edgar Link	pending
R26.htm	Edgar Link	pending
R27.htm	Edgar Link	pending
R28.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R29.htm	Edgar Link	pending
R3.htm	Edgar Link	pending
R30.htm	Edgar Link	pending
R31.htm	Edgar Link	pending
R32.htm	Edgar Link	pending
R33.htm	Edgar Link	pending
R34.htm	Edgar Link	pending
R35.htm	Edgar Link	pending
R36.htm	Edgar Link	pending
R37.htm	Edgar Link	pending
R38.htm	Edgar Link	pending
R39.htm	Edgar Link	pending
R4.htm	Edgar Link	pending
R40.htm	Edgar Link	pending
R41.htm	Edgar Link	pending
R42.htm	Edgar Link	pending
R43.htm	Edgar Link	pending
R44.htm	Edgar Link	pending
R45.htm	Edgar Link	pending
R46.htm	Edgar Link	pending
R47.htm	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R77.htm	Edgar Link	pending
R78.htm	Edgar Link	pending
R79.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R80.htm	Edgar Link	pending
R81.htm	Edgar Link	pending
R82.htm	Edgar Link	pending
R83.htm	Edgar Link	pending
R84.htm	Edgar Link	pending
R85.htm	Edgar Link	pending
R86.htm	Edgar Link	pending
R87.htm	Edgar Link	pending
R88.htm	Edgar Link	pending
R89.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
R90.htm	Edgar Link	pending
R91.htm	Edgar Link	pending
R92.htm	Edgar Link	pending
R93.htm	Edgar Link	pending
R94.htm	Edgar Link	pending
R95.htm	Edgar Link	pending
R96.htm	Edgar Link	pending
R97.htm	Edgar Link	pending
R98.htm	Edgar Link	pending
R99.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending
R48.htm	Edgar Link	pending
R49.htm	Edgar Link	pending
R5.htm	Edgar Link	pending
R50.htm	Edgar Link	pending
R51.htm	Edgar Link	pending
R52.htm	Edgar Link	pending
R53.htm	Edgar Link	pending
R54.htm	Edgar Link	pending
R55.htm	Edgar Link	pending
R56.htm	Edgar Link	pending
R57.htm	Edgar Link	pending
R58.htm	Edgar Link	pending
R59.htm	Edgar Link	pending
R6.htm	Edgar Link	pending
R60.htm	Edgar Link	pending
R61.htm	Edgar Link	pending
R62.htm	Edgar Link	pending
R63.htm	Edgar Link	pending
R64.htm	Edgar Link	pending
R65.htm	Edgar Link	pending
R66.htm	Edgar Link	pending
R67.htm	Edgar Link	pending
R68.htm	Edgar Link	pending
R69.htm	Edgar Link	pending
R7.htm	Edgar Link	pending
R70.htm	Edgar Link	pending
R71.htm	Edgar Link	pending
R72.htm	Edgar Link	pending
R73.htm	Edgar Link	pending
R74.htm	Edgar Link	pending
R75.htm	Edgar Link	pending
R76.htm	Edgar Link	pending
R77.htm	Edgar Link	pending
R78.htm	Edgar Link	pending
R79.htm	Edgar Link	pending
R8.htm	Edgar Link	pending
R80.htm	Edgar Link	pending
R81.htm	Edgar Link	pending
R82.htm	Edgar Link	pending
R83.htm	Edgar Link	pending
R84.htm	Edgar Link	pending
R85.htm	Edgar Link	pending
R86.htm	Edgar Link	pending
R87.htm	Edgar Link	pending
R88.htm	Edgar Link	pending
R89.htm	Edgar Link	pending
R9.htm	Edgar Link	pending
R90.htm	Edgar Link	pending
R91.htm	Edgar Link	pending
R92.htm	Edgar Link	pending
R93.htm	Edgar Link	pending
R94.htm	Edgar Link	pending
R95.htm	Edgar Link	pending
R96.htm	Edgar Link	pending
R97.htm	Edgar Link	pending
R98.htm	Edgar Link	pending
R99.htm	Edgar Link	pending
report.css	Edgar Link	pending
Show.js	Edgar Link	pending
FilingSummary.xml	Edgar Link	unprocessable

Create your account

Find Stocks Worth Researching

Deeply Understand Businesses

Value Businesses Intelligently

$BXMT
BLACKSTONE MORTGAGE TRUST, INC. Stock $bxmt

2024 Q3 Form 10-Q Financial Statement

#000106163024000116 Filed on July 24, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BXMT BLACKSTONE MORTGAGE TRUST, INC. Stock $bxmt

2024 Q3 Form 10-Q Financial Statement

#000106163024000116 Filed on July 24, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$BXMT
BLACKSTONE MORTGAGE TRUST, INC. Stock $bxmt