$NMIH
NMI Holdings, Inc. Stock $nmih

$nmih Overview Financials Valuation SEC Filings Company Website

2024 Q1 Form 10-K Financial Statement

#000154790324000035 Filed on February 15, 2024

Income Statement

Concept	2024 Q1	2023 Q4	2023
Revenue	$156.3M	$18.25M	$579.0M
YoY Change	14.24%	36.77%	10.64%
Cost Of Revenue	$3.694M		$22.62M
YoY Change	-44.87%		-729.33%
Gross Profit	$152.6M		$556.4M
YoY Change	17.28%		5.59%
Gross Profit Margin	97.64%		96.09%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$2.996M	$3.041M	$11.50M
YoY Change	7.08%	5.08%	-3.36%
% of Gross Profit	1.96%		2.07%
Operating Expenses	$33.65M	$38.13M	$134.1M
YoY Change	3.31%	25.88%	16.61%
Operating Profit	$118.9M		$422.3M
YoY Change	21.95%		2.51%
Interest Expense	-$8.040M	$8.066M	$32.21M
YoY Change	-200.01%	0.39%	0.15%
% of Operating Profit	-6.76%		7.63%
Other Income/Expense, Net
YoY Change
Pretax Income	$114.6M	$105.2M	$412.7M
YoY Change	19.13%	10.97%	9.38%
Income Tax	$25.52M	$21.77M	$90.59M
% Of Pretax Income	22.27%	20.7%	21.95%
Net Earnings	$89.05M	$83.41M	$322.1M
YoY Change	19.6%	14.36%	9.97%
Net Earnings / Revenue	56.99%	457.13%	55.63%
Basic Earnings Per Share	$1.10	$1.03	$3.91
Diluted Earnings Per Share	$1.09	$1.01	$3.84
COMMON SHARES
Basic Shares Outstanding	80.88M shares	81.08M shares	82.41M shares
Diluted Shares Outstanding	82.10M shares	82.69M shares	83.85M shares

Balance Sheet

Concept	2024 Q1	2023 Q4	2023
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$138.6M	$96.69M	$95.35M
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	$30.31M	$30.25M	$39.35M
YoY Change	-4.78%	-5.26%	-7.04%
Goodwill		$3.244M
YoY Change		0.0%
Intangibles
YoY Change
Long-Term Investments	$2.394B	$2.371B	$2.371B
YoY Change	10.21%	12.94%	12.94%
Other Assets	$1.137M	$1.338M	$1.338M
YoY Change	-48.25%	-38.51%	-38.51%
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$3.006B	$2.941B	$2.941B
YoY Change	14.14%	16.87%	16.87%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$81.83M	$86.19M	$86.19M
YoY Change	16.33%	15.57%	15.57%
Accrued Expenses			$11.40M
YoY Change			-5.79%
Deferred Revenue
YoY Change
Short-Term Debt	$0.00	$0.00	$0.00
YoY Change
Long-Term Debt Due
YoY Change
Total Short-Term Liabilities	$81.83M	$86.19M	$97.59M
YoY Change	16.33%	15.57%	12.59%
LONG-TERM LIABILITIES
Long-Term Debt	$398.0M	$397.6M	$397.6M
YoY Change	0.4%	0.39%	0.39%
Other Long-Term Liabilities	$12.28M	$11.46M	$56.00K
YoY Change	-0.92%	-6.65%	-67.44%
Total Long-Term Liabilities	$410.3M	$409.1M	$397.7M
YoY Change	0.36%	0.18%	0.36%
TOTAL LIABILITIES
Total Short-Term Liabilities	$81.83M	$86.19M	$97.59M
Total Long-Term Liabilities	$410.3M	$409.1M	$397.7M
Total Liabilities	$1.028B	$1.015B	$1.015B
YoY Change	10.86%	12.43%	12.43%
SHAREHOLDERS EQUITY
Retained Earnings	$1.312B	$1.223B
YoY Change	34.52%	35.75%
Common Stock
YoY Change
Preferred Stock
YoY Change
Treasury Stock (at cost)
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.978B	$1.926B	$1.926B
YoY Change
Total Liabilities & Shareholders Equity	$3.006B	$2.941B	$2.941B
YoY Change	14.14%	16.87%	16.87%

Cashflow Statement

Concept	2024 Q1	2023 Q4	2023
OPERATING ACTIVITIES
Net Income	$89.05M	$83.41M	$322.1M
YoY Change	19.6%	14.36%	9.97%
Depreciation, Depletion And Amortization	$2.996M	$3.041M	$11.50M
YoY Change	7.08%	5.08%	-3.36%
Cash From Operating Activities	$111.6M	$30.08M	$342.7M
YoY Change	24.2%	-5.37%	9.35%
INVESTING ACTIVITIES
Capital Expenditures	$2.186M	$1.472M	$9.372M
YoY Change	44.1%	-47.71%	-11.35%
Acquisitions
YoY Change
Other Investing Activities	-$35.57M	-$80.63M	-$190.6M
YoY Change	10.34%	-23.11%	-31.73%
Cash From Investing Activities	-$37.75M	-$82.10M	-$200.0M
YoY Change	11.85%	-23.75%	-30.98%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$91.61M
YoY Change			61.93%
Debt Paid & Issued, Net
YoY Change
Cash From Financing Activities	-30.79M	-27.82M	-$90.42M
YoY Change	76.86%	405.63%	61.96%
NET CHANGE
Cash From Operating Activities	111.6M	30.08M	$342.7M
Cash From Investing Activities	-37.75M	-82.10M	-$200.0M
Cash From Financing Activities	-30.79M	-27.82M	-$90.42M
Net Change In Cash	43.04M	-79.84M	$52.26M
YoY Change	11.27%	-1.9%	-262.21%
FREE CASH FLOW
Cash From Operating Activities	$111.6M	$30.08M	$342.7M
Capital Expenditures	$2.186M	$1.472M	$9.372M
Free Cash Flow	$109.4M	$28.61M	$333.3M
YoY Change	23.86%	-1.26%	10.07%

Facts In Submission

Frame	Concept Type	Concept / XBRL Key	Value	Unit
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	1613727000	usd
CY2022	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	5213000	usd
CY2021	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	5426000	usd
CY2022Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	99836000	usd
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	103551000	usd
CY2023	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	33000	usd
CY2023	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-33000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	481000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	729000	usd
CY2023	us-gaap	Direct Premiums Written DirectPremiumsWritten	619670000	usd
CY2022	us-gaap	Direct Premiums Written DirectPremiumsWritten	577926000	usd
CY2023	us-gaap	Ceded Premiums Written CededPremiumsWritten	139130000	usd
CY2022	us-gaap	Ceded Premiums Written CededPremiumsWritten	117680000	usd
CY2021	us-gaap	Premiums Written Net PremiumsWrittenNet	468511000	usd
CY2021	us-gaap	Direct Premiums Earned DirectPremiumsEarned	536630000	usd
CY2021Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	20320000	usd
CY2023	dei	Entity Central Index Key EntityCentralIndexKey	0001547903
CY2023	dei	Amendment Flag AmendmentFlag	false
CY2023	dei	Document Fiscal Year Focus DocumentFiscalYearFocus	2023
CY2023	dei	Document Fiscal Period Focus DocumentFiscalPeriodFocus	FY
CY2023Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherAssets
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherAssets
CY2022Q1	us-gaap	Operating Lease Right Of Use Asset Statement Of Financial Position Extensible List OperatingLeaseRightOfUseAssetStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherAssets
CY2022Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherLiabilities
CY2023Q4	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherLiabilities
CY2022Q1	us-gaap	Operating Lease Liability Statement Of Financial Position Extensible List OperatingLeaseLiabilityStatementOfFinancialPositionExtensibleList	http://fasb.org/us-gaap/2023#OtherLiabilities
CY2023	dei	Document Annual Report DocumentAnnualReport	true
CY2023	dei	Current Fiscal Year End Date CurrentFiscalYearEndDate	--12-31
CY2023	dei	Document Transition Report DocumentTransitionReport	false
CY2023	dei	Entity File Number EntityFileNumber	001-36174
CY2023	dei	Entity Registrant Name EntityRegistrantName	NMI Holdings, Inc.
CY2023	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2023	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	45-4914248
CY2023	dei	Entity Address Address Line1 EntityAddressAddressLine1	2100 Powell Street
CY2023	dei	Entity Address City Or Town EntityAddressCityOrTown	Emeryville
CY2023	dei	Entity Address State Or Province EntityAddressStateOrProvince	CA
CY2023	dei	Entity Address Postal Zip Code EntityAddressPostalZipCode	94608
CY2023	dei	City Area Code CityAreaCode	855
CY2023	dei	Local Phone Number LocalPhoneNumber	530-6642
CY2023	dei	Security12b Title Security12bTitle	Class A Common Stock, $.01 par value per share
CY2023	dei	Trading Symbol TradingSymbol	NMIH
CY2023	dei	Security Exchange Name SecurityExchangeName	NASDAQ
CY2023	dei	Entity Well Known Seasoned Issuer EntityWellKnownSeasonedIssuer	Yes
CY2023	dei	Entity Voluntary Filers EntityVoluntaryFilers	No
CY2023	dei	Entity Current Reporting Status EntityCurrentReportingStatus	Yes
CY2023	dei	Entity Interactive Data Current EntityInteractiveDataCurrent	Yes
CY2023	dei	Entity Filer Category EntityFilerCategory	Large Accelerated Filer
CY2023	dei	Entity Small Business EntitySmallBusiness	false
CY2023	dei	Entity Emerging Growth Company EntityEmergingGrowthCompany	false
CY2023	dei	Icfr Auditor Attestation Flag IcfrAuditorAttestationFlag	true
CY2023	dei	Document Fin Stmt Error Correction Flag DocumentFinStmtErrorCorrectionFlag	false
CY2023	dei	Entity Shell Company EntityShellCompany	false
CY2023Q2	dei	Entity Public Float EntityPublicFloat	1710584967	usd
CY2024Q1	dei	Entity Common Stock Shares Outstanding EntityCommonStockSharesOutstanding	80879843	shares
CY2023	dei	Auditor Name AuditorName	BDO USA, P.C.
CY2023	dei	Auditor Location AuditorLocation	San Francisco, CA
CY2023	dei	Auditor Firm AuditorFirmId	243
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2542862000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2352747000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2371021000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2099389000	usd
CY2023Q4	us-gaap	Restricted Cash RestrictedCash	1338000	usd
CY2022Q4	us-gaap	Restricted Cash RestrictedCash	2176000	usd
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	96689000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	44426000	usd
CY2023Q4	us-gaap	Premiums Receivable At Carrying Value PremiumsReceivableAtCarryingValue	76456000	usd
CY2022Q4	us-gaap	Premiums Receivable At Carrying Value PremiumsReceivableAtCarryingValue	69680000	usd
CY2023Q4	us-gaap	Accrued Investment Income Receivable AccruedInvestmentIncomeReceivable	19785000	usd
CY2022Q4	us-gaap	Accrued Investment Income Receivable AccruedInvestmentIncomeReceivable	14144000	usd
CY2023Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	62905000	usd
CY2022Q4	us-gaap	Deferred Policy Acquisition Costs DeferredPolicyAcquisitionCosts	58564000	usd
CY2023Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	30252000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	31930000	usd
CY2023Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	3634000	usd
CY2022Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	3634000	usd
CY2023Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	27514000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	21587000	usd
CY2023Q4	nmih	Prepaid Federal Income Taxes PrepaidFederalIncomeTaxes	235286000	usd
CY2022Q4	nmih	Prepaid Federal Income Taxes PrepaidFederalIncomeTaxes	154409000	usd
CY2023Q4	us-gaap	Other Assets OtherAssets	16965000	usd
CY2022Q4	us-gaap	Other Assets OtherAssets	18267000	usd
CY2023Q4	us-gaap	Assets Assets	2940507000	usd
CY2022Q4	us-gaap	Assets Assets	2516030000	usd
CY2023Q4	us-gaap	Secured Debt SecuredDebt	397595000	usd
CY2022Q4	us-gaap	Secured Debt SecuredDebt	396051000	usd
CY2023Q4	us-gaap	Unearned Premiums UnearnedPremiums	92295000	usd
CY2022Q4	us-gaap	Unearned Premiums UnearnedPremiums	123035000	usd
CY2023Q4	us-gaap	Accounts Payable And Accrued Liabilities Current And Noncurrent AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent	86189000	usd
CY2022Q4	us-gaap	Accounts Payable And Accrued Liabilities Current And Noncurrent AccountsPayableAndAccruedLiabilitiesCurrentAndNoncurrent	74576000	usd
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	123974000	usd
CY2022Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	99836000	usd
CY2023Q4	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	1421000	usd
CY2022Q4	us-gaap	Funds Held Under Reinsurance Agreements Liability FundsHeldUnderReinsuranceAgreementsLiability	2674000	usd
CY2023Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	301573000	usd
CY2022Q4	us-gaap	Deferred Income Tax Liabilities Net DeferredIncomeTaxLiabilitiesNet	193859000	usd
CY2023Q4	us-gaap	Other Liabilities OtherLiabilities	11456000	usd
CY2022Q4	us-gaap	Other Liabilities OtherLiabilities	12272000	usd
CY2023Q4	us-gaap	Liabilities Liabilities	1014503000	usd
CY2022Q4	us-gaap	Liabilities Liabilities	902303000	usd
CY2023Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		usd
CY2022Q4	us-gaap	Commitments And Contingencies CommitmentsAndContingencies		usd
CY2022Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2023Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2023Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	87334138	shares
CY2023Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	80881280	shares
CY2022Q4	us-gaap	Common Stock Shares Issued CommonStockSharesIssued	86472742	shares
CY2022Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	83549879	shares
CY2023Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	250000000	shares
CY2022Q4	us-gaap	Common Stock Shares Authorized CommonStockSharesAuthorized	250000000	shares
CY2023Q4	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	873000	usd
CY2022Q4	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	865000	usd
CY2023Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	990816000	usd
CY2022Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	972717000	usd
CY2023Q4	us-gaap	Treasury Stock Common Shares TreasuryStockCommonShares	6452858	shares
CY2022Q4	us-gaap	Treasury Stock Common Shares TreasuryStockCommonShares	2922863	shares
CY2023Q4	us-gaap	Treasury Stock Common Value TreasuryStockCommonValue	148921000	usd
CY2022Q4	us-gaap	Treasury Stock Common Value TreasuryStockCommonValue	56575000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-139917000	usd
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-204323000	usd
CY2023Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	1223153000	usd
CY2022Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	901043000	usd
CY2023Q4	us-gaap	Stockholders Equity StockholdersEquity	1926004000	usd
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	1613727000	usd
CY2023Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	2940507000	usd
CY2022Q4	us-gaap	Liabilities And Stockholders Equity LiabilitiesAndStockholdersEquity	2516030000	usd
CY2023	us-gaap	Premiums Earned Net PremiumsEarnedNet	510768000	usd
CY2022	us-gaap	Premiums Earned Net PremiumsEarnedNet	475266000	usd
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	444294000	usd
CY2023	us-gaap	Net Investment Income NetInvestmentIncome	67512000	usd
CY2022	us-gaap	Net Investment Income NetInvestmentIncome	46406000	usd
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	38072000	usd
CY2023	us-gaap	Gain Loss On Investments GainLossOnInvestments	-33000	usd
CY2022	us-gaap	Gain Loss On Investments GainLossOnInvestments	481000	usd
CY2021	us-gaap	Gain Loss On Investments GainLossOnInvestments	729000	usd
CY2023	us-gaap	Other Income OtherIncome	756000	usd
CY2022	us-gaap	Other Income OtherIncome	1192000	usd
CY2021	us-gaap	Other Income OtherIncome	1977000	usd
CY2023	us-gaap	Revenues Revenues	579003000	usd
CY2022	us-gaap	Revenues Revenues	523345000	usd
CY2021	us-gaap	Revenues Revenues	485072000	usd
CY2023	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	22618000	usd
CY2022	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	-3594000	usd
CY2021	us-gaap	Policyholder Benefits And Claims Incurred Net PolicyholderBenefitsAndClaimsIncurredNet	12305000	usd
CY2023	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	110699000	usd
CY2022	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	117490000	usd
CY2021	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	142303000	usd
CY2023	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	771000	usd
CY2022	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	1094000	usd
CY2021	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	2509000	usd
CY2023	us-gaap	Interest Expense InterestExpense	32212000	usd
CY2022	us-gaap	Interest Expense InterestExpense	32163000	usd
CY2021	us-gaap	Interest Expense InterestExpense	31796000	usd
CY2023	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	0	usd
CY2022	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	1113000	usd
CY2021	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	566000	usd
CY2023	us-gaap	Costs And Expenses CostsAndExpenses	166300000	usd
CY2022	us-gaap	Costs And Expenses CostsAndExpenses	146040000	usd
CY2021	us-gaap	Costs And Expenses CostsAndExpenses	188347000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	412703000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	377305000	usd
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	296725000	usd
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	90593000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	84403000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65595000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.91
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.45
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.70
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.84
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.39
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.65
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	82407000	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84921000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85620000	shares
CY2023	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	83854000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	85999000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86885000	shares
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	usd
CY2023	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	17113000	usd
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-54608000	usd
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	-13768000	usd
CY2023	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	64380000	usd
CY2022	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-205428000	usd
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-51795000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-7000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	101000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	153000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-26000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	380000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	576000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	64406000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-205808000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-52371000	usd
CY2023	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	386516000	usd
CY2022	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	87094000	usd
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	178759000	usd
CY2020Q4	us-gaap	Stockholders Equity StockholdersEquity	1369591000	usd
CY2021	us-gaap	Stock Issued During Period Value Conversion Of Convertible Securities StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	1983000	usd
CY2021	nmih	Stock Issued During Period Value Employee Stock Purchase Plan Netof Tax Withholdings StockIssuedDuringPeriodValueEmployeeStockPurchasePlanNetofTaxWithholdings	-1225000	usd
CY2021	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	16678000	usd
CY2021	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	-13921000	usd
CY2021	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	-52371000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	usd
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	1565786000	usd
CY2022	us-gaap	Stock Issued During Period Value Conversion Of Convertible Securities StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	1768000	usd
CY2022	nmih	Stock Issued During Period Value Employee Stock Purchase Plan Netof Tax Withholdings StockIssuedDuringPeriodValueEmployeeStockPurchasePlanNetofTaxWithholdings	229000	usd
CY2022	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	56575000	usd
CY2022	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	15425000	usd
CY2022	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	-54709000	usd
CY2022	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	-205808000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2023	nmih	Stock Issued During Period Value Employee Stock Purchase Plan Netof Tax Withholdings StockIssuedDuringPeriodValueEmployeeStockPurchasePlanNetofTaxWithholdings	1193000	usd
CY2023	us-gaap	Treasury Stock Value Acquired Cost Method TreasuryStockValueAcquiredCostMethod	92346000	usd
CY2023	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	16914000	usd
CY2023	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	17120000	usd
CY2023	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	64406000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2023Q4	us-gaap	Stockholders Equity StockholdersEquity	1926004000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	usd
CY2023	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	-33000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	481000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	729000	usd
CY2023	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	0	usd
CY2022	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	1113000	usd
CY2021	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	566000	usd
CY2023	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	11541000	usd
CY2022	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	11870000	usd
CY2021	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	11232000	usd
CY2023	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-481000	usd
CY2022	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-5721000	usd
CY2021	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-6733000	usd
CY2023	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1961000	usd
CY2022	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1846000	usd
CY2021	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1861000	usd
CY2023	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	90593000	usd
CY2022	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	84393000	usd
CY2021	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	65510000	usd
CY2023	us-gaap	Share Based Compensation ShareBasedCompensation	16914000	usd
CY2023	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	10549000	usd
CY2022	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	5442000	usd
CY2022	us-gaap	Share Based Compensation ShareBasedCompensation	15425000	usd
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	16678000	usd
CY2023	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	6776000	usd
CY2022	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	9322000	usd
CY2021	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	10579000	usd
CY2023	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	5641000	usd
CY2022	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	2244000	usd
CY2021	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	2038000	usd
CY2023	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	4341000	usd
CY2022	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	-1020000	usd
CY2023	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	5927000	usd
CY2023	us-gaap	Increase Decrease In Prepaid Taxes IncreaseDecreaseInPrepaidTaxes	80877000	usd
CY2022	us-gaap	Increase Decrease In Prepaid Taxes IncreaseDecreaseInPrepaidTaxes	65165000	usd
CY2021	us-gaap	Increase Decrease In Prepaid Taxes IncreaseDecreaseInPrepaidTaxes	42853000	usd
CY2023	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	316000	usd
CY2022	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	-236000	usd
CY2021	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	218000	usd
CY2023	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	-30740000	usd
CY2022	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	-16202000	usd
CY2021	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	20420000	usd
CY2023	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	24138000	usd
CY2022	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	-3715000	usd
CY2021	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	12984000	usd
CY2023	nmih	Increase Decreasein Reinsurance Assetsand Liabilities IncreaseDecreaseinReinsuranceAssetsandLiabilities	859000	usd
CY2022	nmih	Increase Decreasein Reinsurance Assetsand Liabilities IncreaseDecreaseinReinsuranceAssetsandLiabilities	1904000	usd
CY2021	nmih	Increase Decreasein Reinsurance Assetsand Liabilities IncreaseDecreaseinReinsuranceAssetsandLiabilities	683000	usd
CY2023	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	10389000	usd
CY2022	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	1394000	usd
CY2021	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	16908000	usd
CY2023	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	342683000	usd
CY2022	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	313394000	usd
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	325719000	usd
CY2023	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	166224000	usd
CY2022	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	313926000	usd
CY2021	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	10640000	usd
CY2023	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	488562000	usd
CY2022	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	233586000	usd
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	514405000	usd
CY2023	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	320545000	usd
CY2022	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	151635000	usd
CY2021	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	0	usd
CY2023	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	143613000	usd
CY2022	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	116663000	usd
CY2021	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	163103000	usd
CY2023	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	9372000	usd
CY2022	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	10572000	usd
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12238000	usd
CY2023	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-200000000	usd
CY2022	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-289786000	usd
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-374180000	usd
CY2021	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	4201000	usd
CY2023	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	0	usd
CY2022	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	518000	usd
CY2021	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	503000	usd
CY2023	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	9356000	usd
CY2023	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	0	usd
CY2022	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	0	usd
CY2021	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	1108000	usd
CY2023	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	91613000	usd
CY2022	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	56575000	usd
CY2021	us-gaap	Payments For Repurchase Of Common Stock PaymentsForRepurchaseOfCommonStock	0	usd
CY2023	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-90420000	usd
CY2022	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-55828000	usd
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1830000	usd
CY2023	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	52263000	usd
CY2022	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-32220000	usd
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-50291000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	44426000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	76646000	usd
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	126937000	usd
CY2023Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	96689000	usd
CY2022Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	44426000	usd
CY2021Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	76646000	usd
CY2023	us-gaap	Interest Paid Net InterestPaidNet	29500000	usd
CY2022	us-gaap	Interest Paid Net InterestPaidNet	29500000	usd
CY2021	us-gaap	Interest Paid Net InterestPaidNet	29500000	usd
CY2023	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	-20000	usd
CY2022	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	20000	usd
CY2021	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	457000	usd
CY2023Q4	us-gaap	Number Of States In Which Entity Operates NumberOfStatesInWhichEntityOperates	50	state
CY2023	us-gaap	Use Of Estimates UseOfEstimates	<div style="margin-bottom:9pt;text-align:justify;text-indent:36pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-style:italic;font-weight:400;line-height:120%">Use of Estimates</span></div><div style="margin-bottom:9pt;text-align:justify;text-indent:36pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">We use accounting principles and methods that conform to GAAP. We are required to apply significant judgment and make material estimates in the preparation of our financial statements and with regard to various accounting, reporting and disclosure matters. Assumptions and estimates are required to apply these principles where actual measurement is not possible or practical.</span></div>
CY2023Q4	us-gaap	Interest Receivable InterestReceivable	19800000	usd
CY2022Q4	us-gaap	Interest Receivable InterestReceivable	14100000	usd
CY2023	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	3600000	usd
CY2022	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	11900000	usd
CY2021	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	22800000	usd
CY2022	nmih	Premium Deficiency Reserve Expense PremiumDeficiencyReserveExpense	0	usd
CY2023	nmih	Premium Deficiency Reserve Expense PremiumDeficiencyReserveExpense	0	usd
CY2021	nmih	Premium Deficiency Reserve Expense PremiumDeficiencyReserveExpense	0	usd
CY2023Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	27500000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	21600000	usd
CY2023	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	usd
CY2023	us-gaap	Impairment Of Intangible Assets Indefinitelived Excluding Goodwill ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill	0	usd
CY2023	nmih	Premium Receivable Number Of Days To Be Written Off PremiumReceivableNumberOfDaysToBeWrittenOff	P120D
CY2023Q4	nmih	Premium Receivable Write Off Reserve PremiumReceivableWriteOffReserve	2700000	usd
CY2022Q4	nmih	Premium Receivable Write Off Reserve PremiumReceivableWriteOffReserve	2300000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2542862000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	12498000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	184339000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2371021000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2352747000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	1334000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	254692000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2099389000	usd
CY2023Q4	nmih	Debt Securities Corporate Component Of Total Percentage DebtSecuritiesCorporateComponentOfTotalPercentage	1
CY2022Q4	nmih	Debt Securities Corporate Component Of Total Percentage DebtSecuritiesCorporateComponentOfTotalPercentage	1
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	191375000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	189729000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	1237192000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	1162259000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	1050989000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	959633000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	11064000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	11189000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	52242000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	48211000	usd
CY2023Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2542862000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2371021000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	271613000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	270428000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	935615000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	862747000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	1047461000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	875947000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	23296000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	21709000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	74762000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	68558000	usd
CY2022Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2352747000	usd
CY2022Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2099389000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	184300000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	183100000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	254700000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	218500000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions	36	security
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	127266000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	1274000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	523	security
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	1737189000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	183065000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	559	security
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	1864455000	usd
CY2023Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	184339000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions	241	security
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	772198000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	36225000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	367	security
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	1188415000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	218467000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	608	security
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	1960613000	usd
CY2022Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	254692000	usd
CY2023	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	68214000	usd
CY2022	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	47720000	usd
CY2021	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	39385000	usd
CY2023	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	702000	usd
CY2022	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	1314000	usd
CY2021	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	1313000	usd
CY2023	us-gaap	Investment Income Net InvestmentIncomeNet	67512000	usd
CY2022	us-gaap	Investment Income Net InvestmentIncomeNet	46406000	usd
CY2021	us-gaap	Investment Income Net InvestmentIncomeNet	38072000	usd
CY2023	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	0	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	490000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	729000	usd
CY2022	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	9000	usd
CY2021	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	0	usd
CY2021	us-gaap	Direct Premiums Written DirectPremiumsWritten	557050000	usd
CY2021	us-gaap	Ceded Premiums Written CededPremiumsWritten	88539000	usd
CY2022	us-gaap	Premiums Written Net PremiumsWrittenNet	460246000	usd
CY2023	nmih	Reinsurance Retention Policy Term Of Underlying Mortgage Amortization ReinsuranceRetentionPolicyTermOfUnderlyingMortgageAmortization	P10Y
CY2023Q4	nmih	Reinsurance Agreement Optional Termination Right Percent Of Reinsurance Coverage Threshold ReinsuranceAgreementOptionalTerminationRightPercentOfReinsuranceCoverageThreshold	0.10
CY2019Q3	nmih	Initial Reinsurance Coverage InitialReinsuranceCoverage	326905000	usd
CY2023Q4	nmih	Current Reinsurance Coverage CurrentReinsuranceCoverage	159476000	usd
CY2019Q3	nmih	Initial First Layer Retained Loss InitialFirstLayerRetainedLoss	123424000	usd
CY2023Q4	nmih	Current First Layer Retained Loss CurrentFirstLayerRetainedLoss	121751000	usd
CY2020Q4	nmih	Initial Reinsurance Coverage InitialReinsuranceCoverage	242351000	usd
CY2023Q4	nmih	Current Reinsurance Coverage CurrentReinsuranceCoverage	55792000	usd
CY2020Q4	nmih	Initial First Layer Retained Loss InitialFirstLayerRetainedLoss	121777000	usd
CY2023Q4	nmih	Current First Layer Retained Loss CurrentFirstLayerRetainedLoss	121177000	usd
CY2021Q2	nmih	Initial Reinsurance Coverage InitialReinsuranceCoverage	367238000	usd
CY2023Q4	nmih	Current Reinsurance Coverage CurrentReinsuranceCoverage	217630000	usd
CY2021Q2	nmih	Initial First Layer Retained Loss InitialFirstLayerRetainedLoss	163708000	usd
CY2023Q4	nmih	Current First Layer Retained Loss CurrentFirstLayerRetainedLoss	163394000	usd
CY2021Q4	nmih	Initial Reinsurance Coverage InitialReinsuranceCoverage	363596000	usd
CY2023Q4	nmih	Current Reinsurance Coverage CurrentReinsuranceCoverage	310567000	usd
CY2021Q4	nmih	Initial First Layer Retained Loss InitialFirstLayerRetainedLoss	146229000	usd
CY2023Q4	nmih	Current First Layer Retained Loss CurrentFirstLayerRetainedLoss	145858000	usd
CY2023Q4	nmih	Reinsurance Coverage Percentage Of Population With Production Prior To Period Start Date ReinsuranceCoveragePercentageOfPopulationWithProductionPriorToPeriodStartDate	0.01
CY2023Q4	nmih	Reinsurance Coverage Percentage Of Population With Production Prior To Period Start Date ReinsuranceCoveragePercentageOfPopulationWithProductionPriorToPeriodStartDate	0.02
CY2023Q4	us-gaap	Restricted Cash RestrictedCash	1300000	usd
CY2022Q4	us-gaap	Restricted Cash RestrictedCash	2200000	usd
CY2023Q4	nmih	Number Of Excess Of Loss Reinsurance Agreements NumberOfExcessOfLossReinsuranceAgreements	5	reinsuranceagreement
CY2023Q4	nmih	Reinsurance Coverage Percentage Of Population With Production Prior To Period Start Date ReinsuranceCoveragePercentageOfPopulationWithProductionPriorToPeriodStartDate	0.01
CY2023Q4	nmih	Reinsurance Coverage Percentage Of Population With Production Prior To Period Start Date ReinsuranceCoveragePercentageOfPopulationWithProductionPriorToPeriodStartDate	0.01
CY2023Q4	nmih	Number Of Quota Share Reinsurance Treaties NumberOfQuotaShareReinsuranceTreaties	7	quota_share_agreement
CY2023Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	25800000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	19000000	usd
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	124000000	usd
CY2023	nmih	Liabilityfor Paid Claimsand Claims Adjustment Expense Numberof Paid Claims LiabilityforPaidClaimsandClaimsAdjustmentExpenseNumberofPaidClaims	199	claim
CY2023	nmih	Liabilityfor Unpaid Claimsand Claims Adjustment Expense Claims Paid Including Amounts Covered By Insurance LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseClaimsPaidIncludingAmountsCoveredByInsurance	5200000	usd
CY2023	nmih	Liabilityfor Paid Claimsand Claims Adjustment Expense Numberof Covered Claims Included In Numberof Paid Claims LiabilityforPaidClaimsandClaimsAdjustmentExpenseNumberofCoveredClaimsIncludedInNumberofPaidClaims	186	claim
CY2023	nmih	Liabilityfor Unpaid Claimsand Claims Adjustment Expense Claims Paid Including Amounts Covered By Insurance Amount Under Qsr Transaction LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseClaimsPaidIncludingAmountsCoveredByInsuranceAmountUnderQSRTransaction	1000000	usd
CY2023Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefault	5099	loan
CY2023Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default Percent Of Total Policies In Force LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefaultPercentOfTotalPoliciesInForce	0.0081
CY2023Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Total Policies In Force LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsTotalPoliciesInForce	629690	policy
CY2022Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefault	4449	loan
CY2022Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default Percent Of Total Policies In Force LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefaultPercentOfTotalPoliciesInForce	0.0075
CY2022Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Total Policies In Force LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsTotalPoliciesInForce	594142	policy
CY2023	us-gaap	Schedule Of Liability For Unpaid Claims And Claims Adjustment Expense ScheduleOfLiabilityForUnpaidClaimsAndClaimsAdjustmentExpense	<div style="margin-bottom:3pt;text-align:justify;text-indent:36pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:120%">The following table provides a reconciliation of the beginning and ending gross reserve balances for primary insurance claims and claim expenses (benefits):</span></div><div style="margin-bottom:3pt;margin-top:5pt;text-align:center"><table style="border-collapse:collapse;display:inline-table;margin-bottom:5pt;vertical-align:text-bottom;width:100.000%"><tr><td style="width:1.0%"></td><td style="width:51.342%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:14.273%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.518%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:14.273%"></td><td style="width:0.1%"></td><td style="width:0.1%"></td><td style="width:0.518%"></td><td style="width:0.1%"></td><td style="width:1.0%"></td><td style="width:14.276%"></td><td style="width:0.1%"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="15" style="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%">For the years ended December 31,</span></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><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><td colspan="3" style="border-bottom:1pt solid #000000;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><td colspan="3" style="border-top:1pt solid #000;padding:0 1pt"></td><td colspan="3" style="border-bottom:1pt solid #000000;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%">2021</span></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="padding:0 1pt"></td><td colspan="15" style="border-top:1pt solid #000000;padding:2px 1pt;text-align:center;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-style:italic;font-weight:400;line-height:100%">(In Thousands)</span></td></tr><tr><td colspan="3" style="background-color:#cceeff;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%">Beginning balance</span></td><td style="background-color:#cceeff;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="background-color:#cceeff;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%">99,836 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td style="background-color:#cceeff;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%">$</span></td><td style="background-color:#cceeff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">103,551 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#cceeff;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%">90,567 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;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 reinsurance recoverables </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(1)</span></div></td><td colspan="2" style="background-color:#ffffff;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%">(21,587)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">(20,320)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">(17,608)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;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%">Beginning balance, net of reinsurance recoverables</span></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;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%">78,249 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;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%">83,231 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;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%">72,959 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr style="height:15pt"><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;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%">Add claims incurred:</span></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:12pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Claims and claim expenses (benefits) incurred:</span></div></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Current year </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(2)</span></div></td><td colspan="2" style="background-color:#cceeff;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%">78,285 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">45,168 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">23,433 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Prior years</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline"> (3)</span></div></td><td colspan="2" style="background-color:#ffffff;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%">(56,390)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">(48,762)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">(11,128)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;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%">Total claims and claim expenses (benefits) incurred</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline"> (4)</span></div></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;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%">21,895 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;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%">(3,594)</span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;border-top:1pt solid #000000;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%">12,305 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr style="height:15pt"><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;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%">Less claims paid:</span></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt 2px 12.25pt;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%">Claims and claim expenses paid:</span></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Current year </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(2)</span></div></td><td colspan="2" style="background-color:#cceeff;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%">600 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">74 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">16 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Prior years </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(3)</span></div></td><td colspan="2" style="background-color:#ffffff;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%">3,575 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">1,314 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">2,017 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;padding:2px 1pt;text-align:left;vertical-align:bottom"><div style="padding-left:24.75pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">Reinsurance terminations</span></div></td><td colspan="2" style="background-color:#cceeff;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%">(491)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">— </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">— </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;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%">Total claims and claim expenses paid</span></td><td colspan="2" style="background-color:#ffffff;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%">3,684 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">1,388 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">2,033 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr style="height:15pt"><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;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%">Reserve at end of period, net of reinsurance recoverables</span></td><td colspan="2" style="background-color:#ffffff;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%">96,460 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">78,249 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td colspan="2" style="background-color:#ffffff;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%">83,231 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#cceeff;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%">Add reinsurance recoverables </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:6.5pt;font-weight:400;line-height:100%;position:relative;top:-3.5pt;vertical-align:baseline">(1)</span></div></td><td colspan="2" style="background-color:#cceeff;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%">27,514 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">21,587 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#cceeff;padding:0 1pt"></td><td colspan="2" style="background-color:#cceeff;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%">20,320 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr><tr><td colspan="3" style="background-color:#ffffff;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%">Ending balance</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;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%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">123,974 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;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%">99,836 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;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="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;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%">103,551 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"></td><td colspan="3" style="display:none"></td><td colspan="3" style="display:none"></td></tr></table></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(1) Related to ceded losses recoverable under the QSR Transactions. See Note 6, “</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-style:italic;font-weight:400;line-height:120%">Reinsurance</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">” for additional information. </span></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(2) Related to insured loans with their most recent defaults occurring in the current year. For example, if a loan defaulted in a prior year and subsequently cured and later re-defaulted in the current year, the default would be included in the current year. Amounts are presented net of reinsurance and included $70.6 million attributed to net case reserves and $6.3 million attributed to net IBNR reserves for the year ended December 31, 2023, $39.9 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the year ended December 31, 2022, and $18.1 million attributed to net case reserves and $4.7 million attributed to net IBNR reserves for the year ended December 31, 2021.</span></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(3) Related to insured loans with defaults occurring in prior years, which have been continuously in default before the start of the current year. Amounts are presented net of reinsurance and included $50.9 million attributed to net case reserves and $4.5 million attributed to net IBNR reserves for the year ended December 31, 2023, $42.5 million attributed to net case reserves and $4.7 million attributed to net IBNR reserves for the year ended December 31, 2022, and $6.3 million attributed to net case reserves and $5.0 million attributed to net IBNR reserves for the year ended December 31, 2021.</span></div><div style="padding-left:18pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">(4) Excludes a $0.7 million termination fee for the year ended December 31, 2023 incurred in connection with the amendment of the 2020 QSR Transaction.</span></div>
CY2020Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	90567000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	21587000	usd
CY2020Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	17608000	usd
CY2022Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	78249000	usd
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	83231000	usd
CY2023	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	78285000	usd
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-11128000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	usd
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	82407000	shares
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	-3594000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	12305000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	600000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	74000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	16000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	3575000	usd
CY2022	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	1314000	usd
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2017000	usd
CY2023	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Reinsurance Terminations LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations	491000	usd
CY2022	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Reinsurance Terminations LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations	0	usd
CY2021	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Reinsurance Terminations LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations	0	usd
CY2023	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	3684000	usd
CY2022	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	1388000	usd
CY2021	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2033000	usd
CY2023Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	96460000	usd
CY2022Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	78249000	usd
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	83231000	usd
CY2023Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	27514000	usd
CY2022Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	21587000	usd
CY2021Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	20320000	usd
CY2023Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	123974000	usd
CY2022Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	99836000	usd
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	103551000	usd
CY2023	nmih	Current Year Claims And Claims Adjustment Expense Case Reserves CurrentYearClaimsAndClaimsAdjustmentExpenseCaseReserves	70600000	usd
CY2023	nmih	Current Year Claims And Claims Adjustment Expense Incurred But Not Reported CurrentYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	6300000	usd
CY2022	nmih	Current Year Claims And Claims Adjustment Expense Case Reserves CurrentYearClaimsAndClaimsAdjustmentExpenseCaseReserves	39900000	usd
CY2022	nmih	Current Year Claims And Claims Adjustment Expense Incurred But Not Reported CurrentYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	4500000	usd
CY2021	nmih	Current Year Claims And Claims Adjustment Expense Case Reserves CurrentYearClaimsAndClaimsAdjustmentExpenseCaseReserves	18100000	usd
CY2021	nmih	Current Year Claims And Claims Adjustment Expense Incurred But Not Reported CurrentYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	4700000	usd
CY2023	nmih	Prior Year Claims And Claims Adjustment Expense Case Reserves PriorYearClaimsAndClaimsAdjustmentExpenseCaseReserves	50900000	usd
CY2023	nmih	Prior Year Claims And Claims Adjustment Expense Incurred But Not Reported PriorYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	4500000	usd
CY2022	nmih	Prior Year Claims And Claims Adjustment Expense Case Reserves PriorYearClaimsAndClaimsAdjustmentExpenseCaseReserves	42500000	usd
CY2022	nmih	Prior Year Claims And Claims Adjustment Expense Incurred But Not Reported PriorYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	4700000	usd
CY2021	nmih	Prior Year Claims And Claims Adjustment Expense Case Reserves PriorYearClaimsAndClaimsAdjustmentExpenseCaseReserves	6300000	usd
CY2021	nmih	Prior Year Claims And Claims Adjustment Expense Incurred But Not Reported PriorYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	-5000000	usd
CY2023	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	700000	usd
CY2023	nmih	Prior Year Claims And Claims Adjustment Expense Favorable Development On Prior Year Defaults PriorYearClaimsAndClaimsAdjustmentExpenseFavorableDevelopmentOnPriorYearDefaults	56400000	usd
CY2022	nmih	Prior Year Claims And Claims Adjustment Expense Favorable Development On Prior Year Defaults PriorYearClaimsAndClaimsAdjustmentExpenseFavorableDevelopmentOnPriorYearDefaults	48800000	usd
CY2021	nmih	Prior Year Claims And Claims Adjustment Expense Favorable Development On Prior Year Defaults PriorYearClaimsAndClaimsAdjustmentExpenseFavorableDevelopmentOnPriorYearDefaults	11100000	usd
CY2023Q4	nmih	Liabilityfor Prior Year Claimsand Claims Adjustment Expense LiabilityforPriorYearClaimsandClaimsAdjustmentExpense	24000000	usd
CY2023Q4	us-gaap	Shortduration Insurance Contracts Incurred Claims And Allocated Claim Adjustment Expense Net ShortdurationInsuranceContractsIncurredClaimsAndAllocatedClaimAdjustmentExpenseNet	115068000	usd
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84921000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85620000	shares
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.91
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.45
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.70
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	usd
CY2023	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	0	usd
CY2022	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	1113000	usd
CY2021	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	566000	usd
CY2023	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	322110000	usd
CY2022	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	291789000	usd
CY2021	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	230564000	usd
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	82407000	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84921000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85620000	shares
CY2023	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1447000	shares
CY2022	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1078000	shares
CY2021	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1265000	shares
CY2023	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	83854000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	85999000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86885000	shares
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.84
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.39
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.65
CY2023	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	2000	shares
CY2022	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	18000	shares
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	3000	shares
CY2012Q2	us-gaap	Class Of Warrant Or Right Number Of Securities Called By Warrants Or Rights ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights	992000	shares
CY2012Q2	us-gaap	Warrants And Rights Outstanding Term WarrantsAndRightsOutstandingTerm	P10Y
CY2022Q4	us-gaap	Class Of Warrant Or Right Outstanding ClassOfWarrantOrRightOutstanding	0	shares
CY2023Q4	us-gaap	Class Of Warrant Or Right Outstanding ClassOfWarrantOrRightOutstanding	0	shares
CY2023	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Expiration Period SharebasedCompensationArrangementBySharebasedPaymentAwardExpirationPeriod	P10Y
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Award Vesting Period1 ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1	P3Y
CY2023	us-gaap	Share Based Compensation ShareBasedCompensation	16900000	usd
CY2022	us-gaap	Share Based Compensation ShareBasedCompensation	15400000	usd
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	16700000	usd
CY2023	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3600000	usd
CY2022	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3200000	usd
CY2021	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3500000	usd
CY2022Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1146000	shares
CY2022Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	4.93
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CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2023	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2023	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	415000	shares
CY2023	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Exercisesin Period Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisesinPeriodWeightedAverageGrantDateFairValue	3.74
CY2023	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	9.87
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2023	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue	0
CY2023	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2023	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Nonvested Options Expired Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedOptionsExpiredWeightedAverageGrantDateFairValue	0
CY2023	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	731000	shares
CY2023Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	5.61
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CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	700000	shares
CY2023	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	400000	shares
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	8200000	usd
CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	15.53
CY2023	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P3Y9M21D
CY2023Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	10300000	usd
CY2023	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2022	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2023Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	0	usd
CY2023	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	1
CY2023	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.05
CY2023	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	1900000	usd
CY2022	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	2000000	usd
CY2021	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	2000000	usd
CY2023	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	0	usd
CY2022	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	10000	usd
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	85000	usd
CY2023	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	90593000	usd
CY2022	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	84393000	usd
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	65510000	usd
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	90593000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	84403000	usd
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65595000	usd
CY2023	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2022	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2023	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.006
CY2022	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.006
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.005
CY2023	nmih	Effective Income Tax Rate Reconciliation Compensation Share Based And Other Percent EffectiveIncomeTaxRateReconciliationCompensationShareBasedAndOtherPercent	0.004
CY2022	nmih	Effective Income Tax Rate Reconciliation Compensation Share Based And Other Percent EffectiveIncomeTaxRateReconciliationCompensationShareBasedAndOtherPercent	0.005
CY2021	nmih	Effective Income Tax Rate Reconciliation Compensation Share Based And Other Percent EffectiveIncomeTaxRateReconciliationCompensationShareBasedAndOtherPercent	0.006
CY2023	nmih	Effective Income Tax Rate Reconciliation Warrant Gain Loss Percent EffectiveIncomeTaxRateReconciliationWarrantGainLossPercent	0
CY2022	nmih	Effective Income Tax Rate Reconciliation Warrant Gain Loss Percent EffectiveIncomeTaxRateReconciliationWarrantGainLossPercent	0.001
CY2021	nmih	Effective Income Tax Rate Reconciliation Warrant Gain Loss Percent EffectiveIncomeTaxRateReconciliationWarrantGainLossPercent	0
CY2023	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2022	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0.004
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2023	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.220
CY2022	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.224
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.221
CY2023Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Trading Securities DeferredTaxAssetsUnrealizedLossesOnTradingSecurities	36085000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Unrealized Losses On Trading Securities DeferredTaxAssetsUnrealizedLossesOnTradingSecurities	53205000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	8910000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	8898000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	6026000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	6320000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	3957000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	5264000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Other DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther	1369000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Other DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther	1430000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1190000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	957000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	57537000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	76074000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	9169000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	8888000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	48368000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	67186000	usd
CY2023Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Reserves And Accruals DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals	331342000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Reserves And Accruals DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals	242192000	usd
CY2023Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	13586000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	12653000	usd
CY2023Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Software DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware	2496000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Software DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware	4737000	usd
CY2023Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	2517000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1463000	usd
CY2023Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	349941000	usd
CY2022Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	261045000	usd
CY2023Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	301573000	usd
CY2022Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	193859000	usd
CY2023	nmih	Purchases Of Tax And Loss Bonds PurchasesOfTaxAndLossBonds	80900000	usd
CY2022	nmih	Purchases Of Tax And Loss Bonds PurchasesOfTaxAndLossBonds	65200000	usd
CY2021	nmih	Purchases Of Tax And Loss Bonds PurchasesOfTaxAndLossBonds	42900000	usd
CY2023Q4	nmih	Prepaid Federal Income Taxes PrepaidFederalIncomeTaxes	235300000	usd
CY2022Q4	nmih	Prepaid Federal Income Taxes PrepaidFederalIncomeTaxes	154400000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Subject To Expiration DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration	7300000	usd
CY2023Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	9200000	usd
CY2022Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	8900000	usd
CY2022Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	usd
CY2023Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	usd
CY2023Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	105283000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	96258000	usd
CY2023Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	75031000	usd
CY2022Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	64328000	usd
CY2023Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	30252000	usd
CY2022Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	31930000	usd
CY2023	nmih	Capitalized Costs Additions To Software Equipment Leasehold CapitalizedCostsAdditionsToSoftwareEquipmentLeasehold	9900000	usd
CY2022	nmih	Capitalized Costs Additions To Software Equipment Leasehold CapitalizedCostsAdditionsToSoftwareEquipmentLeasehold	11800000	usd
CY2021	nmih	Capitalized Costs Additions To Software Equipment Leasehold CapitalizedCostsAdditionsToSoftwareEquipmentLeasehold	13600000	usd
CY2023	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	11500000	usd
CY2022	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	11900000	usd
CY2021	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	11200000	usd
CY2023Q4	us-gaap	Goodwill Goodwill	3244000	usd
CY2022Q4	us-gaap	Goodwill Goodwill	3244000	usd
CY2022Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	3634000	usd
CY2023Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	3634000	usd
CY2021	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2023	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2022	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	usd
CY2023Q4	nmih	Number Of Operating Leases Corporate Office And Data Center Facility NumberOfOperatingLeasesCorporateOfficeAndDataCenterFacility	2	operatingleaseagreement
CY2023Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	9100000	usd
CY2023Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	11400000	usd
CY2022Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	10400000	usd
CY2022Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	12100000	usd
CY2022Q1	us-gaap	Operating Lease Liability OperatingLeaseLiability	9700000	usd
CY2022Q1	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	9700000	usd
CY2023Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P6Y2M12D
CY2023Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0650
CY2023	us-gaap	Operating Lease Payments OperatingLeasePayments	1500000	usd
CY2022	us-gaap	Operating Lease Payments OperatingLeasePayments	800000	usd
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	2600000	usd
CY2023	us-gaap	Operating Lease Expense OperatingLeaseExpense	2000000	usd
CY2022	us-gaap	Operating Lease Expense OperatingLeaseExpense	2000000	usd
CY2021	us-gaap	Operating Lease Expense OperatingLeaseExpense	2300000	usd
CY2023Q4	us-gaap	Gain Loss On Investments GainLossOnInvestments	0	usd
CY2023	us-gaap	Gain Loss On Investments GainLossOnInvestments	-33000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	2080000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	2128000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Three LesseeOperatingLeaseLiabilityPaymentsDueYearThree	2190000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Four LesseeOperatingLeaseLiabilityPaymentsDueYearFour	2256000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Five LesseeOperatingLeaseLiabilityPaymentsDueYearFive	2322000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due After Year Five LesseeOperatingLeaseLiabilityPaymentsDueAfterYearFive	2995000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	13971000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	2582000	usd
CY2023Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	11389000	usd
CY2023Q4	us-gaap	Lessee Operating Lease Renewal Term LesseeOperatingLeaseRenewalTerm	P5Y
CY2023Q4	nmih	Approved Insurers Minimum Required Assets ApprovedInsurersMinimumRequiredAssets	400000000	usd
CY2023	nmih	Approved Insurers Risked Based Required Assets Primary Insurance Floor ApprovedInsurersRiskedBasedRequiredAssetsPrimaryInsuranceFloor	0.056
CY2023Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	80900000	shares
CY2022Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	83500000	shares
CY2023Q4	nmih	Number Of Votes Per Common Share NumberOfVotesPerCommonShare	1	vote
CY2022Q1	us-gaap	Stock Repurchase Program Authorized Amount1 StockRepurchaseProgramAuthorizedAmount1	125000000	usd
CY2023	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	3500000	shares
CY2023	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	25.93
CY2022	us-gaap	Treasury Stock Shares Acquired TreasuryStockSharesAcquired	2900000	shares
CY2022	us-gaap	Treasury Stock Acquired Average Cost Per Share TreasuryStockAcquiredAverageCostPerShare	19.34
CY2023Q4	us-gaap	Stock Repurchase Program Remaining Authorized Repurchase Amount1 StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1	176900000	usd
CY2023Q4	nmih	Number Of States In Addition To Wisconsin With Minimum Statutory Capital Relative To Rif Requirement NumberOfStatesInAdditionToWisconsinWithMinimumStatutoryCapitalRelativeToRIFRequirement	15	state
CY2023	nmih	Maximum Permitted Rtc Ratio MaximumPermittedRTCRatio	25
CY2023	nmih	Statutory Accounting Practices Statutory Income Loss Amount StatutoryAccountingPracticesStatutoryIncomeLossAmount	-400000	usd
CY2022	nmih	Statutory Accounting Practices Statutory Income Loss Amount StatutoryAccountingPracticesStatutoryIncomeLossAmount	-58000	usd
CY2021	nmih	Statutory Accounting Practices Statutory Income Loss Amount StatutoryAccountingPracticesStatutoryIncomeLossAmount	3000000	usd
CY2023Q4	nmih	Ordinary Dividends Restrictionwith Regardsto Capital Surplus OrdinaryDividendsRestrictionwithRegardstoCapitalSurplus	0.10
CY2023Q1	us-gaap	Premiums Earned Net PremiumsEarnedNet	121754000	usd
CY2023Q2	us-gaap	Premiums Earned Net PremiumsEarnedNet	125985000	usd
CY2023Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	130089000	usd
CY2023Q4	us-gaap	Premiums Earned Net PremiumsEarnedNet	132940000	usd
CY2023	us-gaap	Premiums Earned Net PremiumsEarnedNet	510768000	usd
CY2023Q1	us-gaap	Net Investment Income NetInvestmentIncome	14894000	usd
CY2023Q2	us-gaap	Net Investment Income NetInvestmentIncome	16518000	usd
CY2023Q3	us-gaap	Net Investment Income NetInvestmentIncome	17853000	usd
CY2023Q4	us-gaap	Net Investment Income NetInvestmentIncome	18247000	usd
CY2023	us-gaap	Net Investment Income NetInvestmentIncome	67512000	usd
CY2023Q1	us-gaap	Gain Loss On Investments GainLossOnInvestments	-33000	usd
CY2023Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	0	usd
CY2023Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	0	usd
CY2023Q1	us-gaap	Other Income OtherIncome	164000	usd
CY2023Q2	us-gaap	Other Income OtherIncome	182000	usd
CY2023Q3	us-gaap	Other Income OtherIncome	217000	usd
CY2023Q4	us-gaap	Other Income OtherIncome	193000	usd
CY2023	us-gaap	Other Income OtherIncome	756000	usd
CY2023Q1	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	6701000	usd
CY2023Q2	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	2873000	usd
CY2023Q3	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	4812000	usd
CY2023Q4	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	8232000	usd
CY2023	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	22618000	usd
CY2023Q1	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	25786000	usd
CY2023Q2	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	27448000	usd
CY2023Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	27749000	usd
CY2023Q4	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	29716000	usd
CY2023	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	110699000	usd
CY2023Q1	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	80000	usd
CY2023Q2	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	267000	usd
CY2023Q3	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	239000	usd
CY2023Q4	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	185000	usd
CY2023	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	771000	usd
CY2023Q1	us-gaap	Interest Expense InterestExpense	8039000	usd
CY2023Q2	us-gaap	Interest Expense InterestExpense	8048000	usd
CY2023Q3	us-gaap	Interest Expense InterestExpense	8059000	usd
CY2023Q4	us-gaap	Interest Expense InterestExpense	8066000	usd
CY2023	us-gaap	Interest Expense InterestExpense	32212000	usd
CY2023Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	96173000	usd
CY2023Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	104049000	usd
CY2023Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	107300000	usd
CY2023Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	105181000	usd
CY2023	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	412703000	usd
CY2023Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	21715000	usd
CY2023Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	23765000	usd
CY2023Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	23345000	usd
CY2023Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	21768000	usd
CY2023	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	90593000	usd
CY2023Q1	us-gaap	Net Income Loss NetIncomeLoss	74458000	usd
CY2023Q2	us-gaap	Net Income Loss NetIncomeLoss	80284000	usd
CY2023Q3	us-gaap	Net Income Loss NetIncomeLoss	83955000	usd
CY2023Q4	us-gaap	Net Income Loss NetIncomeLoss	83413000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2023Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.89
CY2023Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.97
CY2023Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.02
CY2023Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	1.03
CY2023	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.91
CY2023Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.88
CY2023Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.95
CY2023Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.00
CY2023Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	1.01
CY2023	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.84
CY2023Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	83600000	shares
CY2023Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	82958000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	82096000	shares
CY2023Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	81005000	shares
CY2023	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	82407000	shares
CY2023Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	84840000	shares
CY2023Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	84190000	shares
CY2023Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	83670000	shares
CY2023Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	82685000	shares
CY2023	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	83854000	shares
CY2022Q1	us-gaap	Premiums Earned Net PremiumsEarnedNet	116495000	usd
CY2022Q2	us-gaap	Premiums Earned Net PremiumsEarnedNet	120870000	usd
CY2022Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	118317000	usd
CY2022Q4	us-gaap	Premiums Earned Net PremiumsEarnedNet	119584000	usd
CY2022	us-gaap	Premiums Earned Net PremiumsEarnedNet	475266000	usd
CY2022Q1	us-gaap	Net Investment Income NetInvestmentIncome	10199000	usd
CY2022Q2	us-gaap	Net Investment Income NetInvestmentIncome	10921000	usd
CY2022Q3	us-gaap	Net Investment Income NetInvestmentIncome	11945000	usd
CY2022Q4	us-gaap	Net Investment Income NetInvestmentIncome	13341000	usd
CY2022	us-gaap	Net Investment Income NetInvestmentIncome	46406000	usd
CY2022Q1	us-gaap	Gain Loss On Investments GainLossOnInvestments	408000	usd
CY2022Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	53000	usd
CY2022Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	14000	usd
CY2022Q4	us-gaap	Gain Loss On Investments GainLossOnInvestments	6000	usd
CY2022	us-gaap	Gain Loss On Investments GainLossOnInvestments	481000	usd
CY2022Q1	us-gaap	Other Income OtherIncome	339000	usd
CY2022Q2	us-gaap	Other Income OtherIncome	376000	usd
CY2022Q3	us-gaap	Other Income OtherIncome	301000	usd
CY2022Q4	us-gaap	Other Income OtherIncome	176000	usd
CY2022	us-gaap	Other Income OtherIncome	1192000	usd
CY2022Q1	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	-619000	usd
CY2022Q2	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	-3036000	usd
CY2022Q3	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	-3389000	usd
CY2022Q4	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	3450000	usd
CY2022	nmih	Policyholder Benefits And Claims Net Property Casualty And Liability PolicyholderBenefitsAndClaimsNetPropertyCasualtyAndLiability	-3594000	usd
CY2022Q1	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	32935000	usd
CY2022Q2	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	30700000	usd
CY2022Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	27144000	usd
CY2022Q4	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	26711000	usd
CY2022	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	117490000	usd
CY2022Q1	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	430000	usd
CY2022Q2	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	336000	usd
CY2022Q3	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	197000	usd
CY2022Q4	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	131000	usd
CY2022	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	1094000	usd
CY2022Q1	us-gaap	Interest Expense InterestExpense	8041000	usd
CY2022Q2	us-gaap	Interest Expense InterestExpense	8051000	usd
CY2022Q3	us-gaap	Interest Expense InterestExpense	8036000	usd
CY2022Q4	us-gaap	Interest Expense InterestExpense	8035000	usd
CY2022	us-gaap	Interest Expense InterestExpense	32163000	usd
CY2022Q1	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	93000	usd
CY2022Q2	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	1020000	usd
CY2022Q3	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	0	usd
CY2022Q4	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	0	usd
CY2022	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	1113000	usd
CY2022Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	86747000	usd
CY2022Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	97189000	usd
CY2022Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	98589000	usd
CY2022Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	94780000	usd
CY2022	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	377305000	usd
CY2022Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	19067000	usd
CY2022Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	21745000	usd
CY2022Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	21751000	usd
CY2022Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	21840000	usd
CY2022	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	84403000	usd
CY2022Q1	us-gaap	Net Income Loss NetIncomeLoss	67680000	usd
CY2022Q2	us-gaap	Net Income Loss NetIncomeLoss	75444000	usd
CY2022Q3	us-gaap	Net Income Loss NetIncomeLoss	76838000	usd
CY2022Q4	us-gaap	Net Income Loss NetIncomeLoss	72940000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2022Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.79
CY2022Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.88
CY2022Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.91
CY2022Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.87
CY2022	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	3.45
CY2022Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.77
CY2022Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.86
CY2022Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.90
CY2022Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.86
CY2022	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	3.39
CY2022Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85953000	shares
CY2022Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85734000	shares
CY2022Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84444000	shares
CY2022Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	83592000	shares
CY2022	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84921000	shares
CY2022Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	87310000	shares
CY2022Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86577000	shares
CY2022Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	85485000	shares
CY2022Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	84809000	shares
CY2022	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	85999000	shares
CY2023Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Cost SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost	2542862000	usd
CY2023Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Fair Value SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue	2371021000	usd
CY2023Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2371021000	usd
CY2023Q4	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	873000	usd
CY2022Q4	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	865000	usd
CY2023Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	990816000	usd
CY2022Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	972717000	usd
CY2023Q4	us-gaap	Treasury Stock Common Value TreasuryStockCommonValue	148921000	usd
CY2022Q4	us-gaap	Treasury Stock Common Value TreasuryStockCommonValue	56575000	usd
CY2023Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-139917000	usd
CY2022Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	-204323000	usd
CY2023Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	1223153000	usd
CY2022Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	901043000	usd
CY2023Q4	us-gaap	Stockholders Equity StockholdersEquity	1926004000	usd
CY2022Q4	us-gaap	Stockholders Equity StockholdersEquity	1613727000	usd
CY2023	us-gaap	Net Income Loss NetIncomeLoss	322110000	usd
CY2022	us-gaap	Net Income Loss NetIncomeLoss	292902000	usd
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	usd
CY2023	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	0	usd
CY2022	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	1113000	usd
CY2021	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	566000	usd

Files In Submission

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$NMIH
NMI Holdings, Inc. Stock $nmih

2024 Q1 Form 10-K Financial Statement

#000154790324000035 Filed on February 15, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NMIH NMI Holdings, Inc. Stock $nmih

2024 Q1 Form 10-K Financial Statement

#000154790324000035 Filed on February 15, 2024

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NMIH
NMI Holdings, Inc. Stock $nmih