$WTM
WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm

$wtm Overview Financials Valuation SEC Filings Company Website

2023 Q2 Form 10-Q Financial Statement

#000077686723000006 Filed on May 09, 2023

Income Statement

Concept	2023 Q2	2023 Q1
Revenue	$378.4M	$531.9M
YoY Change	393.35%	52.45%
Cost Of Revenue	$11.60M	$13.90M
YoY Change	-48.21%	-35.05%
Gross Profit	$366.8M	$518.0M
YoY Change	575.51%	58.17%
Gross Profit Margin	96.93%	97.39%
Selling, General & Admin	$114.2M	$109.9M
YoY Change	-6.93%	18.94%
% of Gross Profit	31.13%	21.22%
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	-$24.10M	-$82.20M
YoY Change	14.76%	-613.75%
% of Gross Profit	-6.57%	-15.87%
Operating Expenses	$344.6M	$320.2M
YoY Change	15.17%	19.34%
Operating Profit	$22.20M	$197.8M
YoY Change	-109.06%	234.12%
Interest Expense	-$16.40M	-$12.60M
YoY Change	62.38%	82.61%
% of Operating Profit	-73.87%	-6.37%
Other Income/Expense, Net
YoY Change
Pretax Income	$17.40M	$199.1M
YoY Change	-107.48%	-1731.97%
Income Tax	$200.0K	$11.90M
% Of Pretax Income	1.15%	5.98%
Net Earnings	$19.60M	$179.5M
YoY Change	-111.58%	437.43%
Net Earnings / Revenue	5.18%	33.75%
Basic Earnings Per Share	$7.65	$69.83
Diluted Earnings Per Share	$7.65	$69.83
COMMON SHARES
Basic Shares Outstanding	2.563M shares	2.568M shares
Diluted Shares Outstanding	2.525M shares	2.539M shares

Balance Sheet

Concept	2023 Q2	2023 Q1
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$154.5M	$202.7M
Short-Term Investments
Other Short-Term Assets
YoY Change
Inventory
Prepaid Expenses
Receivables
Other Receivables
Total Short-Term Assets
YoY Change
LONG-TERM ASSETS
Property, Plant & Equipment
YoY Change
Goodwill	$168.8M	$168.8M
YoY Change	-16.35%	-73.68%
Intangibles	$204.8M	$207.4M
YoY Change	4.38%
Long-Term Investments	$5.633B	$5.435B
YoY Change	39.91%	31.4%
Other Assets
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$8.376B	$7.959B
YoY Change	9.34%	8.19%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable
YoY Change
Accrued Expenses	$65.70M	$52.10M
YoY Change	-31.42%	-35.92%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$65.70M	$52.10M
YoY Change	-31.42%	-35.92%
LONG-TERM LIABILITIES
Long-Term Debt	$566.1M	$556.3M
YoY Change	-8.41%	-19.48%
Other Long-Term Liabilities	$270.4M	$296.0M
YoY Change	-62.42%	9.51%
Total Long-Term Liabilities	$836.5M	$852.3M
YoY Change	-37.46%	-11.33%
TOTAL LIABILITIES
Total Short-Term Liabilities	$65.70M	$52.10M
Total Long-Term Liabilities	$836.5M	$852.3M
Total Liabilities	$4.250B	$3.866B
YoY Change	1.95%	4.85%
SHAREHOLDERS EQUITY
Retained Earnings	$3.381B	$3.367B
YoY Change	24.06%	13.91%
Common Stock	$2.600M	$2.600M
YoY Change	-10.34%	-13.33%
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$3.922B	$3.902B
YoY Change
Total Liabilities & Shareholders Equity	$8.376B	$7.959B
YoY Change	9.34%	8.19%

Cashflow Statement

Concept	2023 Q2	2023 Q1
OPERATING ACTIVITIES
Net Income	$19.60M	$179.5M
YoY Change	-111.58%	437.43%
Depreciation, Depletion And Amortization	-$24.10M	-$82.20M
YoY Change	14.76%	-613.75%
Cash From Operating Activities	$71.10M	$85.60M
YoY Change	30.46%	-306.27%
INVESTING ACTIVITIES
Capital Expenditures
YoY Change
Acquisitions		$0.00
YoY Change
Other Investing Activities	-$126.2M	$11.20M
YoY Change	18.39%	-354.55%
Cash From Investing Activities	-$126.2M	-$96.60M
YoY Change	18.39%	-169.1%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net
YoY Change
Debt Paid & Issued, Net		$20.00M
YoY Change
Cash From Financing Activities	6.900M	-$41.30M
YoY Change	-96.87%	32.8%
NET CHANGE
Cash From Operating Activities	71.10M	$85.60M
Cash From Investing Activities	-126.2M	-$96.60M
Cash From Financing Activities	6.900M	-$41.30M
Net Change In Cash	-48.20M	-$52.30M
YoY Change	-128.61%	-177.14%
FREE CASH FLOW
Cash From Operating Activities	$71.10M	$85.60M
Capital Expenditures
Free Cash Flow
YoY Change

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2023Q1	dei	Entity Central Index Key EntityCentralIndexKey	0000776867
CY2023Q1	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2023Q1	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2023
CY2023Q1	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	Q1
CY2023Q1	dei	Amendment Flag AmendmentFlag	false
CY2023Q1	dei	Document Type DocumentType	10-Q
CY2023Q1	dei	Document Quarterly Report DocumentQuarterlyReport	true
CY2023Q1	dei	Document Period End Date DocumentPeriodEndDate	2023-03-31
CY2023Q1	dei	Document Transition Report DocumentTransitionReport	false
CY2023Q1	dei	Entity File Number EntityFileNumber	1-8993
CY2023Q1	dei	Entity Registrant Name EntityRegistrantName	WHITE MOUNTAINS INSURANCE GROUP, LTD
CY2023Q1	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	D0
CY2023Q1	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	94-2708455
CY2023Q1	dei	Entity Address Address Line1 EntityAddressAddressLine1	23 South Main Street, Suite 3B
CY2023Q1	dei	Entity Address City Or Town EntityAddressCityOrTown	Hanover,
CY2023Q1	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	03755-2053
CY2023Q1	dei	Entity Address State Or Province EntityAddressStateOrProvince	NH
CY2023Q1	dei	City Area Code CityAreaCode	603
CY2023Q1	dei	Local Phone Number LocalPhoneNumber	640-2200
CY2023Q1	dei	Security12b Title Security12bTitle	Common Shares, par value $1.00 per share
CY2023Q1	dei	Trading Symbol TradingSymbol	WTM
CY2023Q1	dei	Security Exchange Name SecurityExchangeName	NYSE
CY2023Q1	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2023Q1	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2023Q1	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2023Q1	dei	Entity Small Business EntitySmallBusiness	false
CY2023Q1	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2023Q1	dei	Entity Shell Company EntityShellCompany	false
CY2023Q2	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	2563384	shares
CY2023Q1	us-gaap	Assets Assets	7959100000	usd
CY2022Q4	us-gaap	Assets Assets	7389300000	usd
CY2023Q1	us-gaap	Liabilities Liabilities	3866300000	usd
CY2022Q4	us-gaap	Liabilities Liabilities	3454300000	usd
CY2023Q1	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2022Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	1
CY2022Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	50000000	shares
CY2023Q1	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	50000000	shares
CY2023Q1	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	2564484	shares
CY2023Q1	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	2564484	shares
CY2022Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	2572156	shares
CY2022Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	2572156	shares
CY2023Q1	us-gaap	Common Stock Value CommonStockValue	2600000	usd
CY2022Q4	us-gaap	Common Stock Value CommonStockValue	2600000	usd
CY2023Q1	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	535200000	usd
CY2022Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	536000000.0	usd
CY2023Q1	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	3367300000	usd
CY2022Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	3211800000	usd
CY2023Q1	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-2700000	usd
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-3500000	usd
CY2023Q1	us-gaap	Stockholders Equity StockholdersEquity	3902400000	usd
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	3746900000	usd
CY2023Q1	us-gaap	Minority Interest MinorityInterest	190400000	usd
CY2022Q4	us-gaap	Minority Interest MinorityInterest	188100000	usd
CY2023Q1	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	4092800000	usd
CY2022Q4	us-gaap	Stockholders Equity Including Portion Attributable To Noncontrolling Interest StockholdersEquityIncludingPortionAttributableToNoncontrollingInterest	3935000000	usd
CY2023Q1	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7959100000	usd
CY2022Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	7389300000	usd
CY2023Q1	us-gaap	Revenues Revenues	531900000	usd
CY2022Q1	us-gaap	Revenues Revenues	260400000	usd
CY2023Q1	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	332800000	usd
CY2022Q1	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	275200000	usd
CY2023Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	199100000	usd
CY2022Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-14800000	usd
CY2023Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11900000	usd
CY2022Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	-2700000	usd
CY2023Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	187200000	usd
CY2022Q1	us-gaap	Income Loss From Continuing Operations Including Portion Attributable To Noncontrolling Interest IncomeLossFromContinuingOperationsIncludingPortionAttributableToNoncontrollingInterest	-12100000	usd
CY2023Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	0	usd
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	3700000	usd
CY2023Q1	us-gaap	Profit Loss ProfitLoss	187200000	usd
CY2022Q1	us-gaap	Profit Loss ProfitLoss	-8400000	usd
CY2023Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	7700000	usd
CY2022Q1	us-gaap	Net Income Loss Attributable To Noncontrolling Interest NetIncomeLossAttributableToNoncontrollingInterest	-41800000	usd
CY2023Q1	us-gaap	Net Income Loss NetIncomeLoss	179500000	usd
CY2022Q1	us-gaap	Net Income Loss NetIncomeLoss	33400000	usd
CY2023Q1	us-gaap	Net Income Loss NetIncomeLoss	179500000	usd
CY2022Q1	us-gaap	Net Income Loss NetIncomeLoss	33400000	usd
CY2023Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	1200000	usd
CY2022Q1	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-400000	usd
CY2023Q1	wtm	Other Comprehensive Income Loss Discontinued Operations Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossDiscontinuedOperationsNetOfTaxPortionAttributableToParent	0	usd
CY2022Q1	wtm	Other Comprehensive Income Loss Discontinued Operations Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossDiscontinuedOperationsNetOfTaxPortionAttributableToParent	-1900000	usd
CY2023Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	180700000	usd
CY2022Q1	us-gaap	Comprehensive Income Net Of Tax Including Portion Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxIncludingPortionAttributableToNoncontrollingInterest	31100000	usd
CY2023Q1	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	400000	usd
CY2022Q1	us-gaap	Comprehensive Income Net Of Tax Attributable To Noncontrolling Interest ComprehensiveIncomeNetOfTaxAttributableToNoncontrollingInterest	-200000	usd
CY2023Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	180300000	usd
CY2022Q1	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	31300000	usd
CY2023Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	69.83
CY2022Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	9.90
CY2023Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	0
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Basic Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerBasicShare	1.20
CY2023Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	69.83
CY2022Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	11.10
CY2023Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	69.83
CY2022Q1	us-gaap	Income Loss From Continuing Operations Per Diluted Share IncomeLossFromContinuingOperationsPerDilutedShare	9.90
CY2023Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	0
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	1.20
CY2023Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	69.83
CY2022Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	11.10
CY2023Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2022Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2023Q1	us-gaap	Profit Loss ProfitLoss	187200000	usd
CY2022Q1	us-gaap	Profit Loss ProfitLoss	-8400000	usd
CY2023Q1	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	112900000	usd
CY2022Q1	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	-8400000	usd
CY2023Q1	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	-3600000	usd
CY2022Q1	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	5700000	usd
CY2023Q1	wtm	Amortizationof Restricted Sharesand Option Awards AmortizationofRestrictedSharesandOptionAwards	3100000	usd
CY2022Q1	wtm	Amortizationof Restricted Sharesand Option Awards AmortizationofRestrictedSharesandOptionAwards	2900000	usd
CY2023Q1	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	-2400000	usd
CY2022Q1	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	4300000	usd
CY2023Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	0	usd
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax IncomeLossFromDiscontinuedOperationsNetOfTax	3700000	usd
CY2023Q1	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	-24700000	usd
CY2022Q1	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	-16000000.0	usd
CY2023Q1	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	365300000	usd
CY2022Q1	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	343600000	usd
CY2023Q1	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	82200000	usd
CY2022Q1	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	71600000	usd
CY2023Q1	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	49100000	usd
CY2022Q1	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	104900000	usd
CY2023Q1	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	501800000	usd
CY2022Q1	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	388200000	usd
CY2023Q1	us-gaap	Increase Decrease In Funds Held Under Reinsurance Agreements IncreaseDecreaseInFundsHeldUnderReinsuranceAgreements	58100000	usd
CY2022Q1	us-gaap	Increase Decrease In Funds Held Under Reinsurance Agreements IncreaseDecreaseInFundsHeldUnderReinsuranceAgreements	75200000	usd
CY2023Q1	wtm	Increase Decrease In Restricted Cash Operating Activities IncreaseDecreaseInRestrictedCashOperatingActivities	-800000	usd
CY2022Q1	wtm	Increase Decrease In Restricted Cash Operating Activities IncreaseDecreaseInRestrictedCashOperatingActivities	0	usd
CY2023Q1	wtm	Increase In Debt Securities Trading And Equity Securities Fvni IncreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	62900000	usd
CY2022Q1	wtm	Increase In Debt Securities Trading And Equity Securities Fvni IncreaseInDebtSecuritiesTradingAndEquitySecuritiesFVNI	0	usd
CY2023Q1	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	30900000	usd
CY2022Q1	us-gaap	Increase Decrease In Trading Securities IncreaseDecreaseInTradingSecurities	0	usd
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CY2022Q1	us-gaap	Increase Decrease In Other Operating Capital Net IncreaseDecreaseInOtherOperatingCapitalNet	55000000.0	usd
CY2023Q1	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	85600000	usd
CY2022Q1	us-gaap	Net Cash Provided By Used In Operating Activities Continuing Operations NetCashProvidedByUsedInOperatingActivitiesContinuingOperations	-45900000	usd
CY2023Q1	us-gaap	Cash Provided By Used In Operating Activities Discontinued Operations CashProvidedByUsedInOperatingActivitiesDiscontinuedOperations	0	usd
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CY2023Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	85600000	usd
CY2022Q1	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	-41500000	usd
CY2023Q1	us-gaap	Payments For Proceeds From Short Term Investments PaymentsForProceedsFromShortTermInvestments	-47600000	usd
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CY2023Q1	wtm	Proceeds From Maturities Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromMaturitiesOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	66800000	usd
CY2022Q1	wtm	Proceeds From Maturities Of Trading Fixed Maturity And Convertible Fixed Maturity Investments ProceedsFromMaturitiesOfTradingFixedMaturityAndConvertibleFixedMaturityInvestments	39000000.0	usd
CY2023Q1	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	2000000.0	usd
CY2022Q1	us-gaap	Proceeds From Sale And Maturity Of Other Investments ProceedsFromSaleAndMaturityOfOtherInvestments	39800000	usd
CY2023Q1	wtm	Payments To Acquire Trading Fixed Maturity And Convertible Fixed Maturity Investments PaymentsToAcquireTradingFixedMaturityAndConvertibleFixedMaturityInvestments	127600000	usd
CY2022Q1	wtm	Payments To Acquire Trading Fixed Maturity And Convertible Fixed Maturity Investments PaymentsToAcquireTradingFixedMaturityAndConvertibleFixedMaturityInvestments	115000000.0	usd
CY2023Q1	wtm	Payments To Acquire Trading Common Equity Securities PaymentsToAcquireTradingCommonEquitySecurities	0	usd
CY2022Q1	wtm	Payments To Acquire Trading Common Equity Securities PaymentsToAcquireTradingCommonEquitySecurities	38000000.0	usd
CY2023Q1	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	146100000	usd
CY2022Q1	us-gaap	Payments To Acquire Other Investments PaymentsToAcquireOtherInvestments	21400000	usd
CY2023Q1	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	11200000	usd
CY2022Q1	us-gaap	Payments For Proceeds From Other Investing Activities PaymentsForProceedsFromOtherInvestingActivities	-4900000	usd
CY2023Q1	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	-96600000	usd
CY2022Q1	us-gaap	Net Cash Provided By Used In Investing Activities Continuing Operations NetCashProvidedByUsedInInvestingActivitiesContinuingOperations	132500000	usd
CY2023Q1	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	0	usd
CY2022Q1	us-gaap	Cash Provided By Used In Investing Activities Discontinued Operations CashProvidedByUsedInInvestingActivitiesDiscontinuedOperations	7300000	usd
CY2023Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-96600000	usd
CY2022Q1	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	139800000	usd
CY2023Q1	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	0	usd
CY2022Q1	us-gaap	Proceeds From Lines Of Credit ProceedsFromLinesOfCredit	2000000.0	usd
CY2023Q1	us-gaap	Repayments Of Debt RepaymentsOfDebt	20000000.0	usd
CY2022Q1	us-gaap	Repayments Of Debt RepaymentsOfDebt	1300000	usd
CY2023Q1	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	2600000	usd
CY2022Q1	us-gaap	Payments Of Dividends Common Stock PaymentsOfDividendsCommonStock	3000000.0	usd
CY2023Q1	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	25300000	usd
CY2022Q1	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	39000000.0	usd
CY2023Q1	us-gaap	Proceeds From Payments To Minority Shareholders ProceedsFromPaymentsToMinorityShareholders	-1700000	usd
CY2022Q1	us-gaap	Proceeds From Payments To Minority Shareholders ProceedsFromPaymentsToMinorityShareholders	400000	usd
CY2023Q1	wtm	Contributions From Discontinued Operations Financing Activities ContributionsFromDiscontinuedOperationsFinancingActivities	0	usd
CY2022Q1	wtm	Contributions From Discontinued Operations Financing Activities ContributionsFromDiscontinuedOperationsFinancingActivities	9700000	usd
CY2023Q1	wtm	Members Capital Contribution MembersCapitalContribution	11800000	usd
CY2022Q1	wtm	Members Capital Contribution MembersCapitalContribution	12300000	usd
CY2023Q1	wtm	Fidus Re Premium Payment FidusRePremiumPayment	3500000	usd
CY2022Q1	wtm	Fidus Re Premium Payment FidusRePremiumPayment	1900000	usd
CY2023Q1	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-41300000	usd
CY2022Q1	us-gaap	Net Cash Provided By Used In Financing Activities Continuing Operations NetCashProvidedByUsedInFinancingActivitiesContinuingOperations	-20800000	usd
CY2023Q1	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	0	usd
CY2022Q1	us-gaap	Cash Provided By Used In Financing Activities Discontinued Operations CashProvidedByUsedInFinancingActivitiesDiscontinuedOperations	-10300000	usd
CY2023Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-41300000	usd
CY2022Q1	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-31100000	usd
CY2023Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-52300000	usd
CY2022Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	65800000	usd
CY2022Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	12200000	usd
CY2021Q4	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	4500000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	255000000.0	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	147700000	usd
CY2023Q1	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	13000000.0	usd
CY2022Q1	us-gaap	Restricted Cash And Cash Equivalents RestrictedCashAndCashEquivalents	4500000	usd
CY2023Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	202700000	usd
CY2022Q1	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	213500000	usd
CY2023Q1	us-gaap	Interest Paid Net InterestPaidNet	5800000	usd
CY2022Q1	us-gaap	Interest Paid Net InterestPaidNet	5500000	usd
CY2023Q1	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	17800000	usd
CY2022Q1	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	300000	usd
CY2023Q1	us-gaap	Number Of Reportable Segments NumberOfReportableSegments	3	segment
CY2023Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	39600000	usd
CY2022Q1	us-gaap	Interest And Dividend Income Operating InterestAndDividendIncomeOperating	21000000.0	usd
CY2023Q1	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	600000	usd
CY2022Q1	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	400000	usd
CY2023Q1	us-gaap	Net Investment Income NetInvestmentIncome	39000000.0	usd
CY2022Q1	us-gaap	Net Investment Income NetInvestmentIncome	20600000	usd
CY2023Q1	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	46700000	usd
CY2022Q1	us-gaap	Realized Investment Gains Losses RealizedInvestmentGainsLosses	17400000	usd
CY2023Q1	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	151400000	usd
CY2022Q1	us-gaap	Unrealized Gain Loss On Investments UnrealizedGainLossOnInvestments	-9100000	usd
CY2023Q1	wtm	Gain Loss On Investments Exchange Rate Effect GainLossOnInvestmentsExchangeRateEffect	5400000	usd
CY2022Q1	wtm	Gain Loss On Investments Exchange Rate Effect GainLossOnInvestmentsExchangeRateEffect	2600000	usd
CY2023Q1	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Amortized Cost Basis HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateAmortizedCostBasis	2081200000	usd
CY2023Q1	us-gaap	Held To Maturity Securities Debt Maturities Single Maturity Date Fair Value HeldToMaturitySecuritiesDebtMaturitiesSingleMaturityDateFairValue	1955900000	usd
CY2023Q1	wtm	Percentage Of Investments Recorded At Fair Value PercentageOfInvestmentsRecordedAtFairValue	0.70
CY2022	wtm	Percentage Of Investments Recorded At Fair Value PercentageOfInvestmentsRecordedAtFairValue	0.72
CY2023Q1	wtm	Investments Held In Trusts InvestmentsHeldInTrusts	517500000	usd
CY2022Q4	wtm	Investments Held In Trusts InvestmentsHeldInTrusts	500500000	usd
CY2023Q1	us-gaap	Assets Held By Insurance Regulators AssetsHeldByInsuranceRegulators	4600000	usd
CY2022Q4	us-gaap	Assets Held By Insurance Regulators AssetsHeldByInsuranceRegulators	4600000	usd
CY2023Q1	us-gaap	Other Long Term Investments OtherLongTermInvestments	1643000000	usd
CY2022Q4	us-gaap	Other Long Term Investments OtherLongTermInvestments	1488000000	usd
CY2023Q1	us-gaap	Goodwill Fair Value Disclosure GoodwillFairValueDisclosure	168800000	usd
CY2023Q1	us-gaap	Goodwill Goodwill	168800000	usd
CY2022Q4	us-gaap	Goodwill Fair Value Disclosure GoodwillFairValueDisclosure	176500000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	176500000	usd
CY2022Q1	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2023Q1	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2023Q1	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	<div style="text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The following table summarizes the loss and loss adjustment expense (“LAE”) reserve activity of the Ark/WM Outrigger segment</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%"> </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">for the three months ended March 31, 2023 and 2022:</span></div><div><span><br/></span></div><div style="text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:91.812%"><tr><td style="width:1.0%"/><td style="width:65.778%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.596%"/><td style="width:0.1%"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td style="width:1.0%"/><td style="width:14.664%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.596%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:14.666%"/><td style="width:0.1%"/></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="9" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Three Months Ended March 31,</span></td></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">Millions</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2023</span></td><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:700;line-height:100%">2022</span></td></tr><tr><td colspan="3" style="border-top:1pt solid #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Gross beginning balance</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">1,296.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">894.7 </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Less: beginning reinsurance recoverable on unpaid losses </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(505.0)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(428.9)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 13pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Net loss and LAE reserves</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">791.5</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">465.8 </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Loss and LAE incurred relating to:</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 13pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Current year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">139.2</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">125.7 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 13pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Prior year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">8.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(3.7)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Net incurred losses and LAE</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">147.8</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">122.0 </span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Loss and LAE paid relating to:</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 13pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Current year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(4.0)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(.6)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt 2px 13pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Prior year losses</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(87.7)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(39.4)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Net paid loss and LAE</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">(91.7)</span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(40.0)</span></td><td style="border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Change in TPC Providers’ participation </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(2)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">145.4</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">57.5 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Foreign currency translation and other adjustments to loss and LAE<br/> reserves</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">3.7</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">(1.7)</span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr style="height:3pt"><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="padding:0 1pt"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Net ending balance</span></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">996.7</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">603.6 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:6pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Plus: ending reinsurance recoverable on unpaid losses </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:100%;position:relative;top:-2.8pt;vertical-align:baseline">(3)</span></div></td><td colspan="3" style="padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">348.9</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="padding:0 1pt"/><td colspan="2" style="padding:2px 0 2px 1pt;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">396.0 </span></td><td style="padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr><tr><td colspan="3" style="border-bottom:3pt double #000;padding:2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Gross ending balance</span></td><td colspan="3" style="border-bottom:3pt double #000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">$</span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:100%">1,345.6</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%"> </span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="border-bottom:3pt double #000;padding:0 1pt"/><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">999.6 </span></td><td style="border-bottom:3pt double #000;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/></tr></table></div><div style="margin-top:3pt;padding-left:31.5pt;padding-right:31.5pt;text-indent:-9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> The beginning reinsurance recoverable on unpaid losses includes amounts attributable to TPC Providers of $145.4 and $276.8 as of December 31, 2022 and 2021.</span></div><div style="padding-left:31.5pt;padding-right:31.5pt;text-indent:-9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(2)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> Amount represents the impact to net loss and LAE reserves due to a change in the TPC Providers’ participation related to the annual reinsurance to close process.</span></div><div style="padding-left:31.5pt;padding-right:31.5pt;text-indent:-9pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(3)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> The ending reinsurance recoverable on unpaid losses includes amounts attributable to TPC Providers of $0.0 and $207.3 as of March 31, 2023 and 2022.</span></div>
CY2023Q1	us-gaap	Long Term Debt LongTermDebt	556300000	usd
CY2022Q4	us-gaap	Long Term Debt LongTermDebt	575200000	usd
CY2023Q1	wtm	Debt Covenant Loan To Value Maximum Percent Period One DebtCovenantLoanToValueMaximumPercentPeriodOne	0.50
CY2023Q1	wtm	Debt Covenant Loan To Value Maximum Percent Period Two DebtCovenantLoanToValueMaximumPercentPeriodTwo	0.40
CY2023Q1	wtm	Debt Covenant Loan To Value Maximum Percent Period Three DebtCovenantLoanToValueMaximumPercentPeriodThree	0.25
CY2023Q1	wtm	Debt Covenant Loan To Value Maximum Percent Period Four DebtCovenantLoanToValueMaximumPercentPeriodFour	0.15
CY2023Q1	wtm	Debt Covenant Loan To Value Maximum Percent Period Five DebtCovenantLoanToValueMaximumPercentPeriodFive	0
CY2023Q1	wtm	Debt Covenant Loan To Value Maximum Percent DebtCovenantLoanToValueMaximumPercent	0.288
CY2023Q1	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.060
CY2022Q1	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.182
CY2023Q1	wtm	Percentageof Risk Premium Ceded PercentageofRiskPremiumCeded	0.60
CY2018	wtm	Insurance Linked Securities Term InsuranceLinkedSecuritiesTerm	P12Y
CY2018	wtm	Insurance Linked Securities Callable Term InsuranceLinkedSecuritiesCallableTerm	P5Y
CY2021	wtm	Insurance Linked Securities Term InsuranceLinkedSecuritiesTerm	P12Y
CY2021	wtm	Insurance Linked Securities Callable Term InsuranceLinkedSecuritiesCallableTerm	P5Y
CY2022	wtm	Insurance Linked Securities Term InsuranceLinkedSecuritiesTerm	P12Y
CY2022	wtm	Insurance Linked Securities Callable Term InsuranceLinkedSecuritiesCallableTerm	P7Y
CY2023Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Noncontrolling Interest IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest	0	usd
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Noncontrolling Interest IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToNoncontrollingInterest	-100000	usd
CY2023Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	179500000	usd
CY2022Q1	us-gaap	Net Income Loss Available To Common Stockholders Basic NetIncomeLossAvailableToCommonStockholdersBasic	33400000	usd
CY2023Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	0	usd
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Attributable To Reporting Entity IncomeLossFromDiscontinuedOperationsNetOfTaxAttributableToReportingEntity	-3700000	usd
CY2023Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	179500000	usd
CY2022Q1	us-gaap	Income Loss From Continuing Operations IncomeLossFromContinuingOperations	29800000	usd
CY2023Q1	wtm	Income Loss Allocated To Participating Unvested Restricted Common Shares IncomeLossAllocatedToParticipatingUnvestedRestrictedCommonShares	-2200000	usd
CY2022Q1	wtm	Income Loss Allocated To Participating Unvested Restricted Common Shares IncomeLossAllocatedToParticipatingUnvestedRestrictedCommonShares	-300000	usd
CY2023Q1	wtm	Net Income Loss Attributableto Parent Basicand Diluted Earnings Per Share Numerators NetIncomeLossAttributabletoParentBasicandDilutedEarningsPerShareNumerators	177300000	usd
CY2022Q1	wtm	Net Income Loss Attributableto Parent Basicand Diluted Earnings Per Share Numerators NetIncomeLossAttributabletoParentBasicandDilutedEarningsPerShareNumerators	29500000	usd
CY2023Q1	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	2569900	shares
CY2022Q1	us-gaap	Weighted Average Number Of Shares Issued Basic WeightedAverageNumberOfSharesIssuedBasic	3006200	shares
CY2023Q1	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	31100	shares
CY2022Q1	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	29600	shares
CY2023Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	2538800	shares
CY2022Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	2976600	shares
CY2023Q1	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	2569900	shares
CY2022Q1	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	3006200	shares
CY2023Q1	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	31100	shares
CY2022Q1	us-gaap	Weighted Average Number Of Shares Restricted Stock WeightedAverageNumberOfSharesRestrictedStock	29600	shares
CY2023Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	2538800	shares
CY2022Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	2976600	shares
CY2023Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2022Q1	us-gaap	Common Stock Dividends Per Share Declared CommonStockDividendsPerShareDeclared	1.00
CY2023Q1	us-gaap	Earnings Per Share Diluted Undistributed EarningsPerShareDilutedUndistributed	68.83
CY2022Q1	us-gaap	Earnings Per Share Diluted Undistributed EarningsPerShareDilutedUndistributed	8.90
CY2023Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	69.83
CY2022Q1	us-gaap	Income Loss From Continuing Operations Per Basic Share IncomeLossFromContinuingOperationsPerBasicShare	9.90
CY2023Q1	wtm	Net Income Loss Attributableto Parent Netof Restricted Common Share Amounts NetIncomeLossAttributabletoParentNetofRestrictedCommonShareAmounts	177300000	usd
CY2022Q1	wtm	Net Income Loss Attributableto Parent Netof Restricted Common Share Amounts NetIncomeLossAttributabletoParentNetofRestrictedCommonShareAmounts	29500000	usd
CY2023Q1	us-gaap	Dividends Dividends	2500000	usd
CY2022Q1	us-gaap	Dividends Dividends	3000000.0	usd
CY2023Q1	us-gaap	Undistributed Earnings UndistributedEarnings	174800000	usd
CY2022Q1	us-gaap	Undistributed Earnings UndistributedEarnings	26500000	usd
CY2023Q1	us-gaap	Minority Interest MinorityInterest	190400000	usd
CY2022Q4	us-gaap	Minority Interest MinorityInterest	188100000	usd
CY2023Q1	us-gaap	Number Of Operating Segments NumberOfOperatingSegments	3	segment
CY2023Q1	us-gaap	Premiums Earned Net PremiumsEarnedNet	262800000	usd
CY2023Q1	us-gaap	Net Investment Income NetInvestmentIncome	39000000.0	usd
CY2023Q1	wtm	Net Investment Income Expense Debt Interest NetInvestmentIncomeExpenseDebtInterest	0	usd
CY2023Q1	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	112900000	usd
CY2023Q1	us-gaap	Gain Loss On Investments GainLossOnInvestments	85200000	usd
CY2023Q1	wtm	Commission Revenue CommissionRevenue	3300000	usd
CY2023Q1	us-gaap	Other Income OtherIncome	28700000	usd
CY2023Q1	us-gaap	Revenues Revenues	531900000	usd
CY2023Q1	wtm	Insurance Loss And Loss Adjustments Expense InsuranceLossAndLossAdjustmentsExpense	147800000	usd
CY2023Q1	wtm	Insurance And Reinsurance Acquisition Expenses InsuranceAndReinsuranceAcquisitionExpenses	62500000	usd
CY2023Q1	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	13900000	usd
CY2023Q1	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	96000000.0	usd
CY2023Q1	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	-2400000	usd
CY2023Q1	us-gaap	Interest Expense Debt InterestExpenseDebt	15000000.0	usd
CY2023Q1	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	332800000	usd
CY2023Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	199100000	usd
CY2022Q1	us-gaap	Premiums Earned Net PremiumsEarnedNet	202800000	usd
CY2022Q1	us-gaap	Net Investment Income NetInvestmentIncome	20600000	usd
CY2022Q1	wtm	Net Investment Income Expense Debt Interest NetInvestmentIncomeExpenseDebtInterest	0	usd
CY2022Q1	wtm	Gain Loss On Investments Net Of Tax GainLossOnInvestmentsNetOfTax	-8400000	usd
CY2022Q1	us-gaap	Gain Loss On Investments GainLossOnInvestments	18800000	usd
CY2022Q1	wtm	Commission Revenue CommissionRevenue	2900000	usd
CY2022Q1	us-gaap	Other Income OtherIncome	23700000	usd
CY2022Q1	us-gaap	Revenues Revenues	260400000	usd
CY2022Q1	wtm	Insurance Loss And Loss Adjustments Expense InsuranceLossAndLossAdjustmentsExpense	122000000.0	usd
CY2022Q1	wtm	Insurance And Reinsurance Acquisition Expenses InsuranceAndReinsuranceAcquisitionExpenses	52900000	usd
CY2022Q1	us-gaap	Cost Of Goods And Services Sold CostOfGoodsAndServicesSold	21400000	usd
CY2022Q1	us-gaap	General And Administrative Expense GeneralAndAdministrativeExpense	69900000	usd
CY2022Q1	us-gaap	Business Combination Contingent Consideration Arrangements Change In Amount Of Contingent Consideration Liability1 BusinessCombinationContingentConsiderationArrangementsChangeInAmountOfContingentConsiderationLiability1	2100000	usd
CY2022Q1	us-gaap	Interest Expense Debt InterestExpenseDebt	6900000	usd
CY2022Q1	us-gaap	Benefits Losses And Expenses BenefitsLossesAndExpenses	275200000	usd
CY2022Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	-14800000	usd
CY2023Q1	us-gaap	Loss Contingency Disclosures LossContingencyDisclosures	Commitments and Contingencies<div><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Legal Contingencies</span></div><div><span><br/></span></div><div style="text-indent:18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">White Mountains, and the insurance industry in general, is routinely subject to claims related litigation and arbitration in the normal course of business, as well as litigation and arbitration that do not arise from, nor are directly related to, claims activity. White Mountains’s estimates of the costs of settling matters routinely encountered in claims activity are reflected in the reserves for unpaid loss and LAE. See </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:700;line-height:120%">Note 5 — “Losses and Loss Adjustment Expense Reserves.”</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%"> </span></div>White Mountains considers the requirements of ASC 450 when evaluating its exposure to non-claims related litigation and arbitration. ASC 450 requires that accruals be established for litigation and arbitration if it is probable that a loss has been incurred and it can be reasonably estimated. ASC 450 also requires that litigation and arbitration be disclosed if it is probable that a loss has been incurred or if there is a reasonable possibility that a loss may have been incurred. White Mountains does not have any current non-claims related litigation that may have a material adverse effect on White Mountains’s financial condition, results of operations or cash flows.
CY2022Q1	us-gaap	Income Loss From Discontinued Operations Net Of Tax Per Diluted Share IncomeLossFromDiscontinuedOperationsNetOfTaxPerDilutedShare	1.20

Files In Submission

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wtm-20230331_cal.xml	Edgar Link	unprocessable
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0000776867-23-000006.txt	Edgar Link	pending
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$WTM
WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm

2023 Q2 Form 10-Q Financial Statement

#000077686723000006 Filed on May 09, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$WTM WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm

2023 Q2 Form 10-Q Financial Statement

#000077686723000006 Filed on May 09, 2023

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$WTM
WHITE MOUNTAINS INSURANCE GROUP LTD Stock $wtm