$NMIH
NMI Holdings, Inc. Stock $nmih

$nmih Overview Financials Valuation SEC Filings Company Website

2021 Q4 Form 10-K Financial Statement

#000154790322000060 Filed on February 16, 2022

Income Statement

Concept	2021 Q4	2021 Q3	2021
Revenue	$10.05M	$124.0M	$485.1M
YoY Change	19.78%	15.08%	11.95%
Cost Of Revenue		$3.204M	$12.31M
YoY Change
Gross Profit		$120.8M	$472.8M
YoY Change
Gross Profit Margin		97.42%	97.46%
Selling, General & Admin
YoY Change
% of Gross Profit
Research & Development
YoY Change
% of Gross Profit
Depreciation & Amortization	$2.982M	$2.906M	$11.20M
YoY Change	19.28%	16.24%	13.13%
% of Gross Profit		2.4%	2.37%
Operating Expenses	$38.99M	$38.66M	$157.1M
YoY Change	-0.02%	-22.99%	-18.89%
Operating Profit		$82.18M	$315.7M
YoY Change
Interest Expense	$8.029M	$7.930M	$31.80M
YoY Change	1.56%	1.72%	30.38%
% of Operating Profit		9.65%	10.07%
Other Income/Expense, Net
YoY Change
Pretax Income	$78.16M	$77.45M	$296.7M
YoY Change	26.85%	56.92%	36.05%
Income Tax	$17.64M	$17.26M	$65.60M
% Of Pretax Income	22.57%	22.28%	22.11%
Net Earnings	$60.52M	$60.19M	$231.1M
YoY Change	25.39%	57.66%	34.72%
Net Earnings / Revenue	602.52%	48.53%	47.65%
Basic Earnings Per Share	$0.71	$0.70	$2.70
Diluted Earnings Per Share	$0.69	$0.69	$2.65
COMMON SHARES
Basic Shares Outstanding	85.76M shares	85.72M shares	85.62M shares
Diluted Shares Outstanding	87.12M shares	86.88M shares	86.89M shares

Balance Sheet

Concept	2021 Q4	2021 Q3	2021
SHORT-TERM ASSETS
Cash & Short-Term Investments
YoY Change
Cash & Equivalents	$76.65M	$97.26M	$73.48M
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	$32.05M	$32.07M	$34.65M
YoY Change	8.03%	13.99%	1.01%
Goodwill	$3.244M
YoY Change	0.0%
Intangibles
YoY Change
Long-Term Investments	$2.086B	$2.054B	$2.086B
YoY Change	15.61%	21.58%	15.61%
Other Assets			$3.165M
YoY Change
Total Long-Term Assets
YoY Change
TOTAL ASSETS
Total Short-Term Assets
Total Long-Term Assets
Total Assets	$2.451B	$2.398B	$2.451B
YoY Change	13.1%	15.2%	13.1%
SHORT-TERM LIABILITIES
YoY Change
Accounts Payable	$72.00M	$78.66M	$72.00M
YoY Change	16.69%	32.64%	16.69%
Accrued Expenses			$2.900M
YoY Change			-45.28%
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	$72.00M	$78.66M	$74.90M
YoY Change	16.69%	32.64%	11.79%
LONG-TERM LIABILITIES
Long-Term Debt	$394.6M	$394.3M	$394.6M
YoY Change	0.34%	0.33%	0.34%
Other Long-Term Liabilities	$5.608M	$7.277M	$2.708M
YoY Change	-50.81%	-33.24%	-55.61%
Total Long-Term Liabilities	$400.2M	$401.6M	$397.3M
YoY Change	-1.1%	-0.58%	-0.52%
TOTAL LIABILITIES
Total Short-Term Liabilities	$72.00M	$78.66M	$74.90M
Total Long-Term Liabilities	$400.2M	$401.6M	$397.3M
Total Liabilities	$884.8M	$882.1M	$884.8M
YoY Change	11.01%	13.93%	11.0%
SHAREHOLDERS EQUITY
Retained Earnings	$608.1M	$547.6M
YoY Change	61.31%	66.58%
Common Stock
YoY Change
Preferred Stock
YoY Change
Treasury Stock (at cost)	$0.00
YoY Change
Treasury Stock Shares
Shareholders Equity	$1.566B	$1.516B	$1.566B
YoY Change
Total Liabilities & Shareholders Equity	$2.451B	$2.398B	$2.451B
YoY Change	13.1%	15.2%	13.1%

Cashflow Statement

Concept	2021 Q4	2021 Q3	2021
OPERATING ACTIVITIES
Net Income	$60.52M	$60.19M	$231.1M
YoY Change	25.39%	57.66%	34.72%
Depreciation, Depletion And Amortization	$2.982M	$2.906M	$11.20M
YoY Change	19.28%	16.24%	13.13%
Cash From Operating Activities	$44.34M	$98.84M	$325.7M
YoY Change	17.92%	12.83%	28.95%
INVESTING ACTIVITIES
Capital Expenditures	-$3.131M	-$3.057M	$12.24M
YoY Change	1.0%	-32.07%	0.65%
Acquisitions
YoY Change
Other Investing Activities	-$60.53M	-$66.78M	-$361.9M
YoY Change	-42.68%	-83.39%	-41.38%
Cash From Investing Activities	-$63.66M	-$69.84M	-$374.2M
YoY Change	-41.44%	-82.82%	-40.56%
FINANCING ACTIVITIES
Cash Dividend Paid
YoY Change
Common Stock Issuance & Retirement, Net			$0.00
YoY Change			-100.0%
Debt Paid & Issued, Net			$0.00
YoY Change			-100.0%
Cash From Financing Activities	-1.292M	184.0K	-$1.830M
YoY Change	-134.0%	-108.0%	-100.4%
NET CHANGE
Cash From Operating Activities	44.34M	98.84M	$325.7M
Cash From Investing Activities	-63.66M	-69.84M	-$374.2M
Cash From Financing Activities	-1.292M	184.0K	-$1.830M
Net Change In Cash	-20.61M	29.18M	-$50.29M
YoY Change	-69.37%	-109.08%	-158.58%
FREE CASH FLOW
Cash From Operating Activities	$44.34M	$98.84M	$325.7M
Capital Expenditures	-$3.131M	-$3.057M	$12.24M
Free Cash Flow	$47.47M	$101.9M	$313.5M
YoY Change	16.63%	10.63%	30.38%

Facts In Submission

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CY2021	dei	Entity File Number EntityFileNumber	001-36174
CY2021	dei	Entity Registrant Name EntityRegistrantName	NMI Holdings, Inc.
CY2021	dei	Entity Incorporation State Country Code EntityIncorporationStateCountryCode	DE
CY2021	dei	Entity Tax Identification Number EntityTaxIdentificationNumber	45-4914248
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CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodTax	8548000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	35000	USD
CY2021	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	-51795000	USD
CY2020	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	35829000	USD
CY2019	us-gaap	Other Comprehensive Income Unrealized Holding Gain Loss On Securities Arising During Period Net Of Tax OtherComprehensiveIncomeUnrealizedHoldingGainLossOnSecuritiesArisingDuringPeriodNetOfTax	32155000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	153000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	-196000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesTax	9000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	576000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Reclassification Adjustment From Aoci For Sale Of Securities Net Of Tax OtherComprehensiveIncomeLossReclassificationAdjustmentFromAOCIForSaleOfSecuritiesNetOfTax	-739000	USD
CY2021	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	-52371000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	36568000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeLossNetOfTaxPortionAttributableToParent	32120000	USD
CY2021	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	178759000	USD
CY2020	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	208134000	USD
CY2019	us-gaap	Comprehensive Income Net Of Tax ComprehensiveIncomeNetOfTax	204077000	USD
CY2018Q4	us-gaap	Stockholders Equity StockholdersEquity	701500000	USD
CY2019	us-gaap	Stock Issued During Period Value Conversion Of Convertible Securities StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	8312000	USD
CY2019	nmih	Stock Issued During Period Value Employee Stock Purchase Plan Netof Tax Withholdings StockIssuedDuringPeriodValueEmployeeStockPurchasePlanNetofTaxWithholdings	3500000	USD
CY2019	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	13031000	USD
CY2019	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	8539000	USD
CY2019	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	32120000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	171957000	USD
CY2019Q4	us-gaap	Stockholders Equity StockholdersEquity	930420000	USD
CY2020	us-gaap	Stock Issued During Period Value New Issues StockIssuedDuringPeriodValueNewIssues	219687000	USD
CY2020	us-gaap	Stock Issued During Period Value Conversion Of Convertible Securities StockIssuedDuringPeriodValueConversionOfConvertibleSecurities	325000	USD
CY2020	nmih	Stock Issued During Period Value Employee Stock Purchase Plan Netof Tax Withholdings StockIssuedDuringPeriodValueEmployeeStockPurchasePlanNetofTaxWithholdings	-90000	USD
CY2020	us-gaap	Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value AdjustmentsToAdditionalPaidInCapitalSharebasedCompensationRequisiteServicePeriodRecognitionValue	11115000	USD
CY2020	us-gaap	Other Comprehensive Income Loss Available For Sale Securities Tax OtherComprehensiveIncomeLossAvailableForSaleSecuritiesTax	9721000	USD
CY2020	us-gaap	Other Comprehensive Income Availableforsale Securities Adjustment Net Of Tax Portion Attributable To Parent OtherComprehensiveIncomeAvailableforsaleSecuritiesAdjustmentNetOfTaxPortionAttributableToParent	36568000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	171566000	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
CY2020Q4	us-gaap	Common Stock Par Or Stated Value Per Share CommonStockParOrStatedValuePerShare	0.01
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	171566000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	171957000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	729000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	930000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	45000	USD
CY2021	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	-566000	USD
CY2020	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	-2907000	USD
CY2019	us-gaap	Fair Value Adjustment Of Warrants FairValueAdjustmentOfWarrants	8657000	USD
CY2021	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	11232000	USD
CY2020	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	9930000	USD
CY2019	us-gaap	Depreciation Amortization And Accretion Net DepreciationAmortizationAndAccretionNet	9299000	USD
CY2021	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-6733000	USD
CY2020	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-3668000	USD
CY2019	us-gaap	Accretion Amortization Of Discounts And Premiums Investments AccretionAmortizationOfDiscountsAndPremiumsInvestments	-1252000	USD
CY2021	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1861000	USD
CY2020	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	4036000	USD
CY2019	us-gaap	Amortization Of Financing Costs And Discounts AmortizationOfFinancingCostsAndDiscounts	1011000	USD
CY2021	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	65510000	USD
CY2020	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	46506000	USD
CY2019	us-gaap	Deferred Income Taxes And Tax Credits DeferredIncomeTaxesAndTaxCredits	45082000	USD
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	16678000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	11115000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	13031000	USD
CY2021	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	10579000	USD
CY2020	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	3694000	USD
CY2019	us-gaap	Increase Decrease In Premiums Receivable IncreaseDecreaseInPremiumsReceivable	10078000	USD
CY2021	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	2038000	USD
CY2020	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	3031000	USD
CY2019	us-gaap	Increase Decrease In Accrued Investment Income Receivable IncreaseDecreaseInAccruedInvestmentIncomeReceivable	1137000	USD
CY2021	us-gaap	Increase Decrease In Prepaid Expense IncreaseDecreaseInPrepaidExpense	238000	USD
CY2020	us-gaap	Increase Decrease In Prepaid Expense IncreaseDecreaseInPrepaidExpense	-220000	USD
CY2019	us-gaap	Increase Decrease In Prepaid Expense IncreaseDecreaseInPrepaidExpense	472000	USD
CY2021	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	-2641000	USD
CY2020	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	2253000	USD
CY2019	us-gaap	Increase Decrease In Deferred Policy Acquisition Costs IncreaseDecreaseInDeferredPolicyAcquisitionCosts	13132000	USD
CY2021	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	2712000	USD
CY2020	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	12669000	USD
CY2019	us-gaap	Increase Decrease In Reinsurance Recoverable IncreaseDecreaseInReinsuranceRecoverable	1939000	USD
CY2021	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	42833000	USD
CY2020	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	38804000	USD
CY2019	us-gaap	Increase Decrease In Prepaid Deferred Expense And Other Assets IncreaseDecreaseInPrepaidDeferredExpenseAndOtherAssets	8831000	USD
CY2021	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	20420000	USD
CY2020	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	-17825000	USD
CY2019	us-gaap	Increase Decrease In Unearned Premiums IncreaseDecreaseInUnearnedPremiums	-22251000	USD
CY2021	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	12984000	USD
CY2020	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	66815000	USD
CY2019	us-gaap	Increase Decrease In Liability For Claims And Claims Adjustment Expense Reserve IncreaseDecreaseInLiabilityForClaimsAndClaimsAdjustmentExpenseReserve	10941000	USD
CY2021	nmih	Increase Decreasein Reinsurance Assetsand Liabilities IncreaseDecreaseinReinsuranceAssetsandLiabilities	683000	USD
CY2020	nmih	Increase Decreasein Reinsurance Assetsand Liabilities IncreaseDecreaseinReinsuranceAssetsandLiabilities	-2783000	USD
CY2019	nmih	Increase Decreasein Reinsurance Assetsand Liabilities IncreaseDecreaseinReinsuranceAssetsandLiabilities	-917000	USD
CY2021	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	16908000	USD
CY2020	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	18072000	USD
CY2019	us-gaap	Increase Decrease In Accounts Payable And Accrued Liabilities IncreaseDecreaseInAccountsPayableAndAccruedLiabilities	3888000	USD
CY2021	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	325719000	USD
CY2020	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	252598000	USD
CY2019	us-gaap	Net Cash Provided By Used In Operating Activities NetCashProvidedByUsedInOperatingActivities	208150000	USD
CY2021	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	10640000	USD
CY2020	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	42241000	USD
CY2019	us-gaap	Payments To Acquire Short Term Investments PaymentsToAcquireShortTermInvestments	230362000	USD
CY2021	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	514405000	USD
CY2020	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	1065916000	USD
CY2019	us-gaap	Payments To Acquire Available For Sale Securities Debt PaymentsToAcquireAvailableForSaleSecuritiesDebt	290533000	USD
CY2021	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	0	USD
CY2020	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	86045000	USD
CY2019	us-gaap	Proceeds From Sale Of Short Term Investments ProceedsFromSaleOfShortTermInvestments	244921000	USD
CY2021	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	163103000	USD
CY2020	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	404717000	USD
CY2019	us-gaap	Proceeds From Sale And Maturity Of Available For Sale Securities ProceedsFromSaleAndMaturityOfAvailableForSaleSecurities	91575000	USD
CY2021	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12238000	USD
CY2020	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	12159000	USD
CY2019	us-gaap	Payments To Acquire Property Plant And Equipment PaymentsToAcquirePropertyPlantAndEquipment	9956000	USD
CY2021	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-374180000	USD
CY2020	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-629554000	USD
CY2019	us-gaap	Net Cash Provided By Used In Investing Activities NetCashProvidedByUsedInInvestingActivities	-194355000	USD
CY2021	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	219687000	USD
CY2019	us-gaap	Proceeds From Issuance Of Common Stock ProceedsFromIssuanceOfCommonStock	0	USD
CY2021	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	4201000	USD
CY2020	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	8871000	USD
CY2019	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	21748000	USD
CY2021	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	503000	USD
CY2020	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	0	USD
CY2019	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	0	USD
CY2021	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	5426000	USD
CY2020	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	8961000	USD
CY2019	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	18248000	USD
CY2021	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	0	USD
CY2020	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	400000000	USD
CY2019	us-gaap	Proceeds From Issuance Of Senior Long Term Debt ProceedsFromIssuanceOfSeniorLongTermDebt	0	USD
CY2019	nmih	Premium Deficiency Reserve Expense PremiumDeficiencyReserveExpense	0	USD
CY2021	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	0	USD
CY2020	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	147750000	USD
CY2019	us-gaap	Repayments Of Secured Debt RepaymentsOfSecuredDebt	1500000	USD
CY2021	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	1108000	USD
CY2020	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	9043000	USD
CY2019	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	0	USD
CY2021	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	-1830000	USD
CY2020	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	462804000	USD
CY2019	us-gaap	Net Cash Provided By Used In Financing Activities NetCashProvidedByUsedInFinancingActivities	2000000	USD
CY2021	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	-50291000	USD
CY2020	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	85848000	USD
CY2019	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents Period Increase Decrease Including Exchange Rate Effect CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalentsPeriodIncreaseDecreaseIncludingExchangeRateEffect	15795000	USD
CY2020Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	126937000	USD
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	41089000	USD
CY2018Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	25294000	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
CY2019Q4	us-gaap	Cash Cash Equivalents Restricted Cash And Restricted Cash Equivalents CashCashEquivalentsRestrictedCashAndRestrictedCashEquivalents	41089000	USD
CY2021	us-gaap	Interest Paid Net InterestPaidNet	29500000	USD
CY2020	us-gaap	Interest Paid Net InterestPaidNet	17561000	USD
CY2019	us-gaap	Interest Paid Net InterestPaidNet	10691000	USD
CY2021	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	457000	USD
CY2020	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	70000	USD
CY2019	us-gaap	Income Taxes Paid Net IncomeTaxesPaidNet	64000	USD
CY2021Q4	us-gaap	Number Of States In Which Entity Operates NumberOfStatesInWhichEntityOperates	50	state
CY2021	us-gaap	Severance Costs1 SeveranceCosts1	3800000	USD
CY2021	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>
CY2021Q4	us-gaap	Interest Receivable InterestReceivable	11900000	USD
CY2021	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	22800000	USD
CY2020	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	19100000	USD
CY2019	us-gaap	Deferred Policy Acquisition Cost Amortization Expense DeferredPolicyAcquisitionCostAmortizationExpense	8400000	USD
CY2020	nmih	Premium Deficiency Reserve Expense PremiumDeficiencyReserveExpense	0	USD
CY2021	nmih	Premium Deficiency Reserve Expense PremiumDeficiencyReserveExpense	0	USD
CY2021Q4	us-gaap	Reinsurance Recoverables Gross ReinsuranceRecoverablesGross	20300000	USD
CY2021	us-gaap	Goodwill Impairment Loss GoodwillImpairmentLoss	0	USD
CY2021	us-gaap	Impairment Of Intangible Assets Indefinitelived Excluding Goodwill ImpairmentOfIntangibleAssetsIndefinitelivedExcludingGoodwill	0	USD
CY2021	nmih	Premium Receivable Number Of Days To Be Written Off PremiumReceivableNumberOfDaysToBeWrittenOff	P120D
CY2021Q4	nmih	Premium Receivable Write Off Reserve PremiumReceivableWriteOffReserve	2300000	USD
CY2020Q4	nmih	Premium Receivable Write Off Reserve PremiumReceivableWriteOffReserve	1600000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2078773000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	30353000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	23195000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2085931000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1730835000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Gain Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax	73963000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Accumulated Gross Unrealized Loss Before Tax AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax	512000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1804286000	USD
CY2021Q4	nmih	Debt Securities Corporate Component Of Total.Percentage DebtSecuritiesCorporateComponentOfTotal.Percentage	1
CY2020Q4	nmih	Debt Securities Corporate Component Of Total.Percentage DebtSecuritiesCorporateComponentOfTotal.Percentage	1
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	81699000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	82201000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	630625000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	644447000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	1215224000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	1207997000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	54901000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	54705000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	96324000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	96581000	USD
CY2021Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	2078773000	USD
CY2021Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	2085931000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsAmortizedCostBasis	57429000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Next Rolling Twelve Months Fair Value AvailableForSaleSecuritiesDebtMaturitiesNextRollingTwelveMonthsFairValue	57949000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveAmortizedCostBasis	507444000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Two Through Five Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearTwoThroughFiveFairValue	536520000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenAmortizedCostBasis	1016230000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling Year Six Through Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingYearSixThroughTenFairValue	1056098000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Amortized Cost Basis AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenAmortizedCostBasis	21261000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Rolling After Year Ten Fair Value AvailableForSaleSecuritiesDebtMaturitiesRollingAfterYearTenFairValue	22539000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Amortized Cost AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateAmortizedCost	128471000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Maturities Without Single Maturity Date Fair Value AvailableForSaleSecuritiesDebtMaturitiesWithoutSingleMaturityDateFairValue	131180000	USD
CY2020Q4	us-gaap	Available For Sale Debt Securities Amortized Cost Basis AvailableForSaleDebtSecuritiesAmortizedCostBasis	1730835000	USD
CY2020Q4	us-gaap	Available For Sale Securities Debt Securities AvailableForSaleSecuritiesDebtSecurities	1804286000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	23200000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	6500000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	512000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	8000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions	276	security
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	1025912000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	16742000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	23	security
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	156118000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	6453000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	299	security
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	1182030000	USD
CY2021Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	23195000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsNumberOfPositions	15	security
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months	48820000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position Less Than12 Months Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss	504000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Number Of Positions DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerNumberOfPositions	2	security
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger	2528000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Continuous Unrealized Loss Position12 Months Or Longer Accumulated Loss DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss	8000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Number Of Positions DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions	17	security
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position DebtSecuritiesAvailableForSaleUnrealizedLossPosition	51348000	USD
CY2020Q4	us-gaap	Debt Securities Available For Sale Unrealized Loss Position Accumulated Loss DebtSecuritiesAvailableForSaleUnrealizedLossPositionAccumulatedLoss	512000	USD
CY2021	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	39385000	USD
CY2020	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	33140000	USD
CY2019	us-gaap	Investment Income Interest And Dividend InvestmentIncomeInterestAndDividend	31332000	USD
CY2021	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	1313000	USD
CY2020	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	1243000	USD
CY2019	us-gaap	Investment Income Investment Expense InvestmentIncomeInvestmentExpense	476000	USD
CY2021	us-gaap	Investment Income Net InvestmentIncomeNet	38072000	USD
CY2020	us-gaap	Investment Income Net InvestmentIncomeNet	31897000	USD
CY2019	us-gaap	Investment Income Net InvestmentIncomeNet	30856000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	729000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	5572000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain DebtSecuritiesAvailableForSaleRealizedGain	561000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	0	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	4642000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Loss DebtSecuritiesAvailableForSaleRealizedLoss	516000	USD
CY2021	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	729000	USD
CY2020	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	930000	USD
CY2019	us-gaap	Debt Securities Available For Sale Realized Gain Loss DebtSecuritiesAvailableForSaleRealizedGainLoss	45000	USD
CY2021	us-gaap	Direct Premiums Written DirectPremiumsWritten	557050000	USD
CY2020	us-gaap	Direct Premiums Written DirectPremiumsWritten	455172000	USD
CY2019	us-gaap	Direct Premiums Written DirectPremiumsWritten	376052000	USD
CY2021	us-gaap	Ceded Premiums Written CededPremiumsWritten	88539000	USD
CY2020	us-gaap	Ceded Premiums Written CededPremiumsWritten	66528000	USD
CY2019	us-gaap	Ceded Premiums Written CededPremiumsWritten	43400000	USD
CY2021	us-gaap	Premiums Written Net PremiumsWrittenNet	468511000	USD
CY2020	us-gaap	Premiums Written Net PremiumsWrittenNet	388644000	USD
CY2019	us-gaap	Premiums Written Net PremiumsWrittenNet	332652000	USD
CY2020	us-gaap	Direct Premiums Earned DirectPremiumsEarned	472998000	USD
CY2019	us-gaap	Direct Premiums Earned DirectPremiumsEarned	398303000	USD
CY2021	us-gaap	Ceded Premiums Earned CededPremiumsEarned	92336000	USD
CY2020	us-gaap	Ceded Premiums Earned CededPremiumsEarned	75826000	USD
CY2019	us-gaap	Ceded Premiums Earned CededPremiumsEarned	53288000	USD
CY2020	us-gaap	Premiums Earned Net PremiumsEarnedNet	397172000	USD
CY2019	us-gaap	Premiums Earned Net PremiumsEarnedNet	345015000	USD
CY2021Q4	us-gaap	Restricted Cash RestrictedCash	3200000	USD
CY2020Q4	us-gaap	Restricted Cash RestrictedCash	5600000	USD
CY2021Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefault	6227	loan
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	103600000	USD
CY2021	nmih	Liabilityfor Paid Claimsand Claims Adjustment Expense Numberof Paid Claims LiabilityforPaidClaimsandClaimsAdjustmentExpenseNumberofPaidClaims	82	claim
CY2021	nmih	Liabilityfor Unpaid Claimsand Claims Adjustment Expense Claims Paid Including Amounts Covered By Insurance LiabilityforUnpaidClaimsandClaimsAdjustmentExpenseClaimsPaidIncludingAmountsCoveredByInsurance	2600000	USD
CY2021Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefault	6227	loan
CY2021Q4	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	0.0122
CY2021Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Total Policies In Force LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsTotalPoliciesInForce	512316	claim
CY2020Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Number Of Primary Loans In Default LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsNumberOfPrimaryLoansInDefault	12209	loan
CY2020Q4	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	0.0306
CY2020Q4	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Incurred But Not Reported Ibnr Claims Total Policies In Force LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredButNotReportedIBNRClaimsTotalPoliciesInForce	399429	policy
CY2021	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:</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 style="width:51.342%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:14.273%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.518%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:14.273%"/><td style="width:0.1%"/><td style="width:0.1%"/><td style="width:0.518%"/><td style="width:0.1%"/><td style="width:1.0%"/><td style="width:14.276%"/><td style="width:0.1%"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr><td colspan="3" style="padding:0 1pt"/><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 year ended </span></td></tr><tr><td colspan="3" style="padding:0 1pt"/><td colspan="3" 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-weight:700;line-height:100%">December 31, 2021</span></td><td colspan="3" style="border-bottom:1pt solid #000;border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-bottom:1pt solid #000000;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-weight:700;line-height:100%">December 31, 2020</span></td><td colspan="3" style="border-bottom:1pt solid #000000;border-top:1pt solid #000;padding:0 1pt"/><td colspan="3" style="border-bottom:1pt solid #000000;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-weight:700;line-height:100%">December 31, 2019</span></td><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr><td colspan="3" style="padding:0 1pt"/><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%">$</span></td><td style="background-color:#cceeff;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">90,567 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td style="background-color:#cceeff;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</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%">23,752 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">12,811 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">(17,608)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">(4,939)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">(3,001)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">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 colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">18,813 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">9,810 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr style="height:15pt"><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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 colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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 incurred:</span></td><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">23,433 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">66,943 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">14,737 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">(11,128)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">(7,696)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">(2,230)</span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">Total claims and claim expenses incurred</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%">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 colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">59,247 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">12,507 </span></td><td style="background-color:#cceeff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr style="height:15pt"><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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 colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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 colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">16 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">586 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">204 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">2,017 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">4,515 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">3,849 </span></td><td style="background-color:#ffffff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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><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;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 colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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 colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">(549)</span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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 #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%">2,033 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;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%">5,101 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;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%">3,504 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></tr><tr style="height:15pt"><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><td colspan="3" style="background-color:#cceeff;border-top:1pt solid #000000;padding:0 1pt"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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;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:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;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:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td colspan="2" style="background-color:#ffffff;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%">18,813 </span></td><td style="background-color:#ffffff;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">20,320 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">17,608 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#cceeff;padding:0 1pt"/><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%">4,939 </span></td><td style="background-color:#cceeff;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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%">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 colspan="3" style="background-color:#ffffff;padding:0 1pt"/><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%">$</span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0;text-align:right;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">90,567 </span></td><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 1pt 2px 0;text-align:right;vertical-align:bottom"/><td colspan="3" style="background-color:#ffffff;padding:0 1pt"/><td style="background-color:#ffffff;border-bottom:3pt double #000000;border-top:1pt solid #000000;padding:2px 0 2px 1pt;text-align:left;vertical-align:bottom"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:10pt;font-weight:400;line-height:100%">$</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%">23,752 </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 colspan="3" style="display:none"/><td colspan="3" style="display:none"/></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:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(1)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> 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:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(2) </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">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 $18.1 million attributed to net case reserves and $4.7 million attributed to net IBNR reserves for the year ended December 31, 2021, $60.8 million attributed to net case reserves and $5.0 million attributed to net IBNR reserves for year ended December 31, 2020, and $13.2 million attributed to net case reserves and $1.3 million attributed to net IBNR reserves for year ended December 31, 2019.</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:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(3) </span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%">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 $6.3 million attributed to net case reserves and $5.0 million attributed to net IBNR reserves for the year ended December 31, 2021, $6.2 million attributed to net case reserves and $1.3 million attributed to net IBNR reserves for the year ended December 31, 2020, and $1.5 million attributed to net case reserves and $0.7 million attributed to net IBNR reserves for year ended December 31, 2019.</span></div><div style="margin-bottom:9pt;padding-left:18pt;text-align:justify;text-indent:-18pt"><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:5.2pt;font-weight:400;line-height:120%;position:relative;top:-2.8pt;vertical-align:baseline">(4)</span><span style="color:#000000;font-family:'Times New Roman',sans-serif;font-size:8pt;font-weight:400;line-height:120%"> Represents the settlement of reinsurance recoverables in conjunction with the termination of one reinsurer under the 2016 QSR Transaction on a cut-off basis. 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>
CY2020Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	90567000	USD
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	23752000	USD
CY2018Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	12811000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	17608000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	4939000	USD
CY2018Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	3001000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	72959000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18813000	USD
CY2018Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	9810000	USD
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	23433000	USD
CY2020	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	66943000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Current Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersCurrentYearClaimsAndClaimsAdjustmentExpense	14737000	USD
CY2021	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-11128000	USD
CY2020	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-7696000	USD
CY2019	us-gaap	Supplemental Information For Property Casualty Insurance Underwriters Prior Year Claims And Claims Adjustment Expense SupplementalInformationForPropertyCasualtyInsuranceUnderwritersPriorYearClaimsAndClaimsAdjustmentExpense	-2230000	USD
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	12305000	USD
CY2020	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	59247000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Incurred Claims1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseIncurredClaims1	12507000	USD
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	16000	USD
CY2020	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	586000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Current Year1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidCurrentYear1	204000	USD
CY2021	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	2017000	USD
CY2020	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	4515000	USD
CY2019	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Prior Years1 LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidPriorYears1	3849000	USD
CY2021	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Reinsurance Terminations LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations	0	USD
CY2020	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Reinsurance Terminations LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations	0	USD
CY2019	nmih	Liability For Unpaid Claims And Claims Adjustment Expense Claims Paid Reinsurance Terminations LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseClaimsPaidReinsuranceTerminations	549000	USD
CY2021	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	2033000	USD
CY2020	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	5101000	USD
CY2019	us-gaap	Payments For Losses And Loss Adjustment Expense PaymentsForLossesAndLossAdjustmentExpense	3504000	USD
CY2021Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	83231000	USD
CY2020Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	72959000	USD
CY2019Q4	us-gaap	Liability For Unpaid Claims And Claims Adjustment Expense Net LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseNet	18813000	USD
CY2021Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	20320000	USD
CY2020Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	17608000	USD
CY2019Q4	us-gaap	Reinsurance Recoverables On Paid And Unpaid Losses ReinsuranceRecoverablesOnPaidAndUnpaidLosses	4939000	USD
CY2021Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	103551000	USD
CY2020Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	90567000	USD
CY2019Q4	us-gaap	Liability For Claims And Claims Adjustment Expense LiabilityForClaimsAndClaimsAdjustmentExpense	23752000	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
CY2020	nmih	Current Year Claims And Claims Adjustment Expense Case Reserves CurrentYearClaimsAndClaimsAdjustmentExpenseCaseReserves	60800000	USD
CY2020	nmih	Current Year Claims And Claims Adjustment Expense Incurred But Not Reported CurrentYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	5000000	USD
CY2019	nmih	Current Year Claims And Claims Adjustment Expense Case Reserves CurrentYearClaimsAndClaimsAdjustmentExpenseCaseReserves	13200000	USD
CY2019	nmih	Current Year Claims And Claims Adjustment Expense Incurred But Not Reported CurrentYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	1300000	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
CY2020	nmih	Prior Year Claims And Claims Adjustment Expense Case Reserves PriorYearClaimsAndClaimsAdjustmentExpenseCaseReserves	-6200000	USD
CY2020	nmih	Prior Year Claims And Claims Adjustment Expense Incurred But Not Reported PriorYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	-1300000	USD
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	67573000	shares
CY2019	nmih	Prior Year Claims And Claims Adjustment Expense Case Reserves PriorYearClaimsAndClaimsAdjustmentExpenseCaseReserves	-1500000	USD
CY2019	nmih	Prior Year Claims And Claims Adjustment Expense Incurred But Not Reported PriorYearClaimsAndClaimsAdjustmentExpenseIncurredButNotReported	-700000	USD
CY2021Q4	nmih	Liabilityfor Prior Year Claimsand Claims Adjustment Expense LiabilityforPriorYearClaimsandClaimsAdjustmentExpense	74400000	USD
CY2021Q4	us-gaap	Shortduration Insurance Contracts Cumulative Paid Claims And Allocated Claim Adjustment Expense Net ShortdurationInsuranceContractsCumulativePaidClaimsAndAllocatedClaimAdjustmentExpenseNet	14743000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	171566000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	171957000	USD
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85620000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	78023000	shares
CY2019	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	67573000	shares
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.70
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.20
CY2019	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.54
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	171566000	USD
CY2019	us-gaap	Net Income Loss NetIncomeLoss	171957000	USD
CY2021	nmih	Gain On Change In Fair Value Of Warrant Liability GainOnChangeInFairValueOfWarrantLiability	566000	USD
CY2020	nmih	Gain On Change In Fair Value Of Warrant Liability GainOnChangeInFairValueOfWarrantLiability	2907000	USD
CY2019	nmih	Gain On Change In Fair Value Of Warrant Liability GainOnChangeInFairValueOfWarrantLiability	0	USD
CY2021	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	230564000	USD
CY2020	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	168659000	USD
CY2019	us-gaap	Net Income Loss Attributable To Parent Diluted NetIncomeLossAttributableToParentDiluted	171957000	USD
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85620000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	78023000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86885000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	79263000	shares
CY2021	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1265000	shares
CY2020	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	1240000	shares
CY2019	us-gaap	Weighted Average Number Diluted Shares Outstanding Adjustment WeightedAverageNumberDilutedSharesOutstandingAdjustment	2148000	shares
CY2019	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	69721000	shares
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.65
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.13
CY2019	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.47
CY2021	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	3000	shares
CY2020	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	58000	shares
CY2019	us-gaap	Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount	565000	shares
CY2012Q2	us-gaap	Class Of Warrant Or Right Number Of Securities Called By Warrants Or Rights ClassOfWarrantOrRightNumberOfSecuritiesCalledByWarrantsOrRights	992000	shares
CY2021Q4	us-gaap	Class Of Warrant Or Right Outstanding ClassOfWarrantOrRightOutstanding	199000	shares
CY2012Q2	nmih	Number Of Shares Right To Purchase Per Warrant NumberOfSharesRightToPurchasePerWarrant	1	shares
CY2012Q2	us-gaap	Class Of Warrant Or Right Exercise Price Of Warrants Or Rights1 ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights1	10.00
CY2012Q2	us-gaap	Warrants And Rights Outstanding WarrantsAndRightsOutstanding	5100000	USD
CY2021	nmih	Classof Warrantor Right Numberof Warrants Exercised During Period ClassofWarrantorRightNumberofWarrantsExercisedDuringPeriod	113000	shares
CY2021	us-gaap	Stock Issued During Period Shares Conversion Of Convertible Securities StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities	86000	shares
CY2021	nmih	Class Of Warrant Or Right Fair Value Of Warrant Liability Reclassified To Additional Paid In Capital Upon Exercise ClassOfWarrantOrRightFairValueOfWarrantLiabilityReclassifiedToAdditionalPaidInCapitalUponExercise	1500000	USD
CY2020	nmih	Classof Warrantor Right Numberof Warrants Exercised During Period ClassofWarrantorRightNumberofWarrantsExercisedDuringPeriod	18000	shares
CY2020	us-gaap	Stock Issued During Period Shares Conversion Of Convertible Securities StockIssuedDuringPeriodSharesConversionOfConvertibleSecurities	11000	shares
CY2020	nmih	Class Of Warrant Or Right Fair Value Of Warrant Liability Reclassified To Additional Paid In Capital Upon Exercise ClassOfWarrantOrRightFairValueOfWarrantLiabilityReclassifiedToAdditionalPaidInCapitalUponExercise	300000	USD
CY2021	nmih	Class Of Warrant Or Right Change In Fair Value Of Warrant Liability In Current Period ClassOfWarrantOrRightChangeInFairValueOfWarrantLiabilityInCurrentPeriod	100000	USD
CY2020	nmih	Class Of Warrant Or Right Change In Fair Value Of Warrant Liability In Current Period ClassOfWarrantOrRightChangeInFairValueOfWarrantLiabilityInCurrentPeriod	100000	USD
CY2019	nmih	Class Of Warrant Or Right Change In Fair Value Of Warrant Liability In Current Period ClassOfWarrantOrRightChangeInFairValueOfWarrantLiabilityInCurrentPeriod	4100000	USD
CY2021	us-gaap	Share Based Compensation ShareBasedCompensation	16700000	USD
CY2020	us-gaap	Share Based Compensation ShareBasedCompensation	11100000	USD
CY2019	us-gaap	Share Based Compensation ShareBasedCompensation	13000000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	3500000	USD
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1371000	shares
CY2020	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	2300000	USD
CY2019	us-gaap	Employee Service Share Based Compensation Tax Benefit From Compensation Expense EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense	2700000	USD
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1493000	shares
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	5.02
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.59
CY2021	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 Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	122000	shares
CY2021	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Exercisesin Period Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisesinPeriodWeightedAverageGrantDateFairValue	-4.43
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	11.42
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue	0
CY2021	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2021	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Nonvested Options Expired Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedOptionsExpiredWeightedAverageGrantDateFairValue	0
CY2021Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	5.07
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.78
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1928000	shares
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	4.84
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.04
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	0
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	0
CY2020	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	435000	shares
CY2020	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Exercisesin Period Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisesinPeriodWeightedAverageGrantDateFairValue	4.21
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	11.17
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2020	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue	0
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2020	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Nonvested Options Expired Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedOptionsExpiredWeightedAverageGrantDateFairValue	0
CY2020	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1493000	shares
CY2020Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	5.02
CY2020Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.59
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	2882000	shares
CY2018Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	4.24
CY2018Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	11.42
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	163000	shares
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Weighted Average Grant Date Fair Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue	8.85
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Grants In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice	22.19
CY2019	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	1117000	shares
CY2019	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Exercisesin Period Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsExercisesinPeriodWeightedAverageGrantDateFairValue	3.88
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Exercises In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice	10.19
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod	0	shares
CY2019	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Options Forfeited Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedOptionsForfeitedWeightedAverageGrantDateFairValue	0
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Forfeitures In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice	0
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageExercisePrice	13.51
CY2019	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Expirations In Period ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod	0	shares
CY2019	nmih	Sharebased Compensation Arrangementby Sharebased Payment Award Options Nonvested Options Expired Weighted Average Grant Date Fair Value SharebasedCompensationArrangementbySharebasedPaymentAwardOptionsNonvestedOptionsExpiredWeightedAverageGrantDateFairValue	0
CY2019	us-gaap	Share Based Compensation Arrangements By Share Based Payment Award Options Expirations In Period Weighted Average Exercise Price ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice	0
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber	1928000	shares
CY2019Q4	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Nonvested Weighted Average Grant Date Fair Value SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsNonvestedWeightedAverageGrantDateFairValue	4.84
CY2019Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Outstanding Weighted Average Exercise Price ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice	13.04
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Number ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableNumber	1300000	shares
CY2021	us-gaap	Stock Issued During Period Shares Stock Options Exercised StockIssuedDuringPeriodSharesStockOptionsExercised	100000	shares
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Exercises In Period Total Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue	1500000	USD
CY2021	us-gaap	Sharebased Compensation Arrangement By Sharebased Payment Award Options Vested And Expected To Vest Exercisable Weighted Average Remaining Contractual Term1 SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsVestedAndExpectedToVestExercisableWeightedAverageRemainingContractualTerm1	P3Y11M12D
CY2021Q4	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Vested And Expected To Vest Exercisable Aggregate Intrinsic Value ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestExercisableAggregateIntrinsicValue	11100000	USD
CY2021Q4	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Stock Options EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedStockOptions	14000	USD
CY2021	us-gaap	Employee Service Share Based Compensation Nonvested Awards Total Compensation Cost Not Yet Recognized Period For Recognition1 EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognizedPeriodForRecognition1	P0Y1M13D
CY2021	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2020	us-gaap	Share Based Compensation Arrangement By Share Based Payment Award Options Grants In Period Gross ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross	0	shares
CY2021	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent Of Match DefinedContributionPlanEmployerMatchingContributionPercentOfMatch	1
CY2021	us-gaap	Defined Contribution Plan Employer Matching Contribution Percent DefinedContributionPlanEmployerMatchingContributionPercent	0.05
CY2021	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	2000000	USD
CY2020	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	2200000	USD
CY2019	us-gaap	Defined Contribution Plan Employer Discretionary Contribution Amount DefinedContributionPlanEmployerDiscretionaryContributionAmount	2500000	USD
CY2021	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	85000	USD
CY2020	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	34000	USD
CY2019	us-gaap	Current Income Tax Expense Benefit CurrentIncomeTaxExpenseBenefit	-386000	USD
CY2021	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	65510000	USD
CY2020	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	46506000	USD
CY2019	us-gaap	Deferred Income Tax Expense Benefit DeferredIncomeTaxExpenseBenefit	45082000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65595000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	46540000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	44696000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65600000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	46500000	USD
CY2019	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	44700000	USD
CY2021	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2020	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2019	us-gaap	Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate EffectiveIncomeTaxRateReconciliationAtFederalStatutoryIncomeTaxRate	0.210
CY2021	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.005
CY2020	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.005
CY2019	us-gaap	Effective Income Tax Rate Reconciliation State And Local Income Taxes EffectiveIncomeTaxRateReconciliationStateAndLocalIncomeTaxes	0.005
CY2020	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
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CY2020	nmih	Effective Income Tax Rate Reconciliation Compensation Share Based And Other Percent EffectiveIncomeTaxRateReconciliationCompensationShareBasedAndOtherPercent	0.001
CY2019	nmih	Effective Income Tax Rate Reconciliation Compensation Share Based And Other Percent EffectiveIncomeTaxRateReconciliationCompensationShareBasedAndOtherPercent	-0.017
CY2021	nmih	Effective Income Tax Rate Reconciliation Warrant Gain Loss Percent EffectiveIncomeTaxRateReconciliationWarrantGainLossPercent	0
CY2020	nmih	Effective Income Tax Rate Reconciliation Warrant Gain Loss Percent EffectiveIncomeTaxRateReconciliationWarrantGainLossPercent	0.003
CY2019	nmih	Effective Income Tax Rate Reconciliation Warrant Gain Loss Percent EffectiveIncomeTaxRateReconciliationWarrantGainLossPercent	-0.009
CY2021	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	0
CY2019	us-gaap	Effective Income Tax Rate Reconciliation Other Adjustments EffectiveIncomeTaxRateReconciliationOtherAdjustments	-0.001
CY2021	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.221
CY2020	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.213
CY2019	us-gaap	Effective Income Tax Rate Continuing Operations EffectiveIncomeTaxRateContinuingOperations	0.206
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	8759000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards DeferredTaxAssetsOperatingLossCarryforwards	7938000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	6090000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Compensation And Benefits Share Based Compensation Cost DeferredTaxAssetsTaxDeferredExpenseCompensationAndBenefitsShareBasedCompensationCost	5067000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	5878000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Unearned Premiums Reserve DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsUnearnedPremiumsReserve	4844000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Other DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther	2852000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Other DeferredTaxAssetsTaxDeferredExpenseReservesAndAccrualsOther	3198000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1067000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Other DeferredTaxAssetsOther	1592000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	24646000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Gross DeferredTaxAssetsGross	22639000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	8582000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	7610000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	16064000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Net DeferredTaxAssetsNet	15029000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Reserves And Accruals DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals	157919000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Reserves And Accruals DeferredTaxLiabilitiesDeferredExpenseReservesAndAccruals	91429000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	12797000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Deferred Policy Acquisition Cost DeferredTaxLiabilitiesDeferredExpenseDeferredPolicyAcquisitionCost	13381000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Software DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware	7286000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Deferred Expense Capitalized Software DeferredTaxLiabilitiesDeferredExpenseCapitalizedSoftware	5569000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	1503000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Investments DeferredTaxLiabilitiesInvestments	15432000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	734000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities Other DeferredTaxLiabilitiesOther	1804000	USD
CY2021Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	180239000	USD
CY2020Q4	us-gaap	Deferred Income Tax Liabilities DeferredIncomeTaxLiabilities	127615000	USD
CY2021Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	164175000	USD
CY2020Q4	us-gaap	Deferred Tax Liabilities DeferredTaxLiabilities	112586000	USD
CY2021	nmih	Purchases Of Tax And Loss Bonds PurchasesOfTaxAndLossBonds	42900000	USD
CY2020	nmih	Purchases Of Tax And Loss Bonds PurchasesOfTaxAndLossBonds	38800000	USD
CY2019	nmih	Purchases Of Tax And Loss Bonds PurchasesOfTaxAndLossBonds	7600000	USD
CY2021Q4	nmih	Tax And Loss Bond TaxAndLossBond	89200000	USD
CY2020Q4	nmih	Tax And Loss Bond TaxAndLossBond	46400000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Operating Loss Carryforwards Subject To Expiration DeferredTaxAssetsOperatingLossCarryforwardsSubjectToExpiration	7300000	USD
CY2021Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	8600000	USD
CY2020Q4	us-gaap	Deferred Tax Assets Valuation Allowance DeferredTaxAssetsValuationAllowance	7600000	USD
CY2021Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2020Q4	us-gaap	Unrecognized Tax Benefits UnrecognizedTaxBenefits	0	USD
CY2021Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	85537000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Gross PropertyPlantAndEquipmentGross	72203000	USD
CY2021Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	53490000	USD
CY2020Q4	us-gaap	Accumulated Depreciation Depletion And Amortization Property Plant And Equipment AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment	42538000	USD
CY2021Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	32047000	USD
CY2020Q4	us-gaap	Property Plant And Equipment Net PropertyPlantAndEquipmentNet	29665000	USD
CY2021	nmih	Capitalized Costs Additions To Software Equipment Leasehold CapitalizedCostsAdditionsToSoftwareEquipmentLeasehold	13600000	USD
CY2020	nmih	Capitalized Costs Additions To Software Equipment Leasehold CapitalizedCostsAdditionsToSoftwareEquipmentLeasehold	14500000	USD
CY2019	nmih	Capitalized Costs Additions To Software Equipment Leasehold CapitalizedCostsAdditionsToSoftwareEquipmentLeasehold	10600000	USD
CY2021	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	11200000	USD
CY2020	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	9900000	USD
CY2019	us-gaap	Depreciation Depletion And Amortization DepreciationDepletionAndAmortization	9300000	USD
CY2020Q4	us-gaap	Goodwill Goodwill	3244000	USD
CY2021Q4	us-gaap	Goodwill Goodwill	3244000	USD
CY2020Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	3634000	USD
CY2021Q4	us-gaap	Intangible Assets Net Including Goodwill IntangibleAssetsNetIncludingGoodwill	3634000	USD
CY2021	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	USD
CY2020	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	USD
CY2019	us-gaap	Goodwill And Intangible Asset Impairment GoodwillAndIntangibleAssetImpairment	0	USD
CY2021Q4	nmih	Approved Insurers Minimum Required Assets ApprovedInsurersMinimumRequiredAssets	400000000	USD
CY2021	nmih	Approved Insurers Risked Based Required Assets Primary Insurance Floor ApprovedInsurersRiskedBasedRequiredAssetsPrimaryInsuranceFloor	0.056
CY2021Q4	nmih	Number Of Operating Leases Corporate Office And Data Center Facility NumberOfOperatingLeasesCorporateOfficeAndDataCenterFacility	2	lease_agreement
CY2021Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	2600000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	2900000	USD
CY2020Q4	us-gaap	Operating Lease Right Of Use Asset OperatingLeaseRightOfUseAsset	4600000	USD
CY2020Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	5300000	USD
CY2019	us-gaap	Right Of Use Asset Obtained In Exchange For Operating Lease Liability RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability	8100000	USD
CY2021Q4	us-gaap	Operating Lease Weighted Average Remaining Lease Term1 OperatingLeaseWeightedAverageRemainingLeaseTerm1	P1Y2M12D
CY2021Q4	us-gaap	Operating Lease Weighted Average Discount Rate Percent OperatingLeaseWeightedAverageDiscountRatePercent	0.0621
CY2021	us-gaap	Operating Lease Payments OperatingLeasePayments	2600000	USD
CY2020	us-gaap	Operating Lease Payments OperatingLeasePayments	2500000	USD
CY2019	us-gaap	Operating Lease Payments OperatingLeasePayments	2500000	USD
CY2021	us-gaap	Operating Lease Expense OperatingLeaseExpense	2300000	USD
CY2020	us-gaap	Operating Lease Expense OperatingLeaseExpense	2300000	USD
CY2019	us-gaap	Operating Lease Expense OperatingLeaseExpense	2200000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Next Twelve Months LesseeOperatingLeaseLiabilityPaymentsDueNextTwelveMonths	2574000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due Year Two LesseeOperatingLeaseLiabilityPaymentsDueYearTwo	462000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Payments Due LesseeOperatingLeaseLiabilityPaymentsDue	3036000	USD
CY2021Q4	us-gaap	Lessee Operating Lease Liability Undiscounted Excess Amount LesseeOperatingLeaseLiabilityUndiscountedExcessAmount	135000	USD
CY2021Q4	us-gaap	Operating Lease Liability OperatingLeaseLiability	2901000	USD
CY2021Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	85800000	shares
CY2020Q4	us-gaap	Common Stock Shares Outstanding CommonStockSharesOutstanding	85200000	shares
CY2021Q4	nmih	Number Of States In Addition To Wisconsin With Minimum Statutory Capital Relative To Rif Requirement NumberOfStatesInAdditionToWisconsinWithMinimumStatutoryCapitalRelativeToRIFRequirement	15	state
CY2021Q4	nmih	Numberof States Which Require Minimum Amountof Statutory Capital Relativeto Risk In Force NumberofStatesWhichRequireMinimumAmountofStatutoryCapitalRelativetoRiskInForce	16	state
CY2019Q1	nmih	Mortgage Insurance Percentageof Indebtednesson Single Loan Limit MortgageInsurancePercentageofIndebtednessonSingleLoanLimit	0.25
CY2021Q4	nmih	Mortgage Insurance Percentageof Indebtednesson Single Loan Limit MortgageInsurancePercentageofIndebtednessonSingleLoanLimit	0.25
CY2021Q4	nmih	Mortgage Insurance Percentageof Indebtednesson Single Loan Limit MortgageInsurancePercentageofIndebtednessonSingleLoanLimit	0.25
CY2021Q4	nmih	Commutation Fees Paid CommutationFeesPaid	8400000	USD
CY2021Q4	nmih	Ordinary Dividends Restrictionwith Regardsto Capital Surplus OrdinaryDividendsRestrictionwithRegardstoCapitalSurplus	0.10
CY2021Q4	nmih	Ordinary Dividends Restrictionwith Regardsto Capital Surplus Next Fiscal Year OrdinaryDividendsRestrictionwithRegardstoCapitalSurplusNextFiscalYear	34900000	USD
CY2021Q1	us-gaap	Premiums Earned Net PremiumsEarnedNet	105879000	USD
CY2021Q2	us-gaap	Premiums Earned Net PremiumsEarnedNet	110888000	USD
CY2021Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	113594000	USD
CY2021Q4	us-gaap	Premiums Earned Net PremiumsEarnedNet	113933000	USD
CY2021	us-gaap	Premiums Earned Net PremiumsEarnedNet	444294000	USD
CY2021Q1	us-gaap	Net Investment Income NetInvestmentIncome	8814000	USD
CY2021Q2	us-gaap	Net Investment Income NetInvestmentIncome	9382000	USD
CY2021Q3	us-gaap	Net Investment Income NetInvestmentIncome	9831000	USD
CY2021Q4	us-gaap	Net Investment Income NetInvestmentIncome	10045000	USD
CY2021	us-gaap	Net Investment Income NetInvestmentIncome	38072000	USD
CY2021Q1	us-gaap	Gain Loss On Investments GainLossOnInvestments	0	USD
CY2021Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	12000	USD
CY2021Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	3000	USD
CY2021Q4	us-gaap	Gain Loss On Investments GainLossOnInvestments	714000	USD
CY2021	us-gaap	Gain Loss On Investments GainLossOnInvestments	729000	USD
CY2021Q1	us-gaap	Other Income OtherIncome	501000	USD
CY2021Q2	us-gaap	Other Income OtherIncome	483000	USD
CY2021Q3	us-gaap	Other Income OtherIncome	613000	USD
CY2021Q4	us-gaap	Other Income OtherIncome	380000	USD
CY2021	us-gaap	Other Income OtherIncome	1977000	USD
CY2021Q1	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	4962000	USD
CY2021Q2	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	4640000	USD
CY2021Q3	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	3204000	USD
CY2021Q4	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	-500000	USD
CY2021	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	12305000	USD
CY2021Q2	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	481000	USD
CY2021Q1	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	34065000	USD
CY2021Q2	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	34725000	USD
CY2021Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	34669000	USD
CY2021Q4	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	38843000	USD
CY2021	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	142303000	USD
CY2021Q1	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	591000	USD
CY2021Q3	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	787000	USD
CY2021Q4	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	650000	USD
CY2021	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	2509000	USD
CY2021Q1	us-gaap	Interest Expense InterestExpense	7915000	USD
CY2021Q2	us-gaap	Interest Expense InterestExpense	7922000	USD
CY2021Q3	us-gaap	Interest Expense InterestExpense	7930000	USD
CY2021Q4	us-gaap	Interest Expense InterestExpense	8029000	USD
CY2021	us-gaap	Interest Expense InterestExpense	31796000	USD
CY2021Q1	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	-205000	USD
CY2021Q2	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	658000	USD
CY2021Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	16133000	USD
CY2021Q3	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	0	USD
CY2021Q4	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	112000	USD
CY2021	nmih	Gain On Change In Fair Value Of Warrant Liability GainOnChangeInFairValueOfWarrantLiability	566000	USD
CY2021Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	67456000	USD
CY2021Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	73655000	USD
CY2021Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	77451000	USD
CY2021Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	78162000	USD
CY2021	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	296725000	USD
CY2021Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	14565000	USD
CY2021Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	17258000	USD
CY2021Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	17639000	USD
CY2021	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	65595000	USD
CY2021Q1	us-gaap	Net Income Loss NetIncomeLoss	52891000	USD
CY2021Q2	us-gaap	Net Income Loss NetIncomeLoss	57522000	USD
CY2021Q3	us-gaap	Net Income Loss NetIncomeLoss	60193000	USD
CY2021Q4	us-gaap	Net Income Loss NetIncomeLoss	60523000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	USD
CY2021Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.62
CY2021Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.67
CY2021Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.70
CY2021Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.71
CY2021	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.70
CY2021Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.61
CY2021Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.65
CY2021Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.69
CY2021Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.69
CY2021	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.65
CY2021Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85317000	shares
CY2021Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85647000	shares
CY2021Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85721000	shares
CY2021Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85757000	shares
CY2021	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	85620000	shares
CY2021Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86487000	shares
CY2021Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86819000	shares
CY2021Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86880000	shares
CY2021Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	87117000	shares
CY2021	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86885000	shares
CY2020Q1	us-gaap	Premiums Earned Net PremiumsEarnedNet	98717000	USD
CY2020Q2	us-gaap	Premiums Earned Net PremiumsEarnedNet	98944000	USD
CY2020Q3	us-gaap	Premiums Earned Net PremiumsEarnedNet	98802000	USD
CY2020Q4	us-gaap	Premiums Earned Net PremiumsEarnedNet	100709000	USD
CY2020	us-gaap	Premiums Earned Net PremiumsEarnedNet	397172000	USD
CY2020Q1	us-gaap	Net Investment Income NetInvestmentIncome	8104000	USD
CY2020Q2	us-gaap	Net Investment Income NetInvestmentIncome	7070000	USD
CY2020	us-gaap	Net Investment Income NetInvestmentIncome	31897000	USD
CY2020Q3	us-gaap	Net Investment Income NetInvestmentIncome	8337000	USD
CY2020Q4	us-gaap	Net Investment Income NetInvestmentIncome	8386000	USD
CY2020Q1	us-gaap	Gain Loss On Investments GainLossOnInvestments	-72000	USD
CY2020Q2	us-gaap	Gain Loss On Investments GainLossOnInvestments	711000	USD
CY2020Q3	us-gaap	Gain Loss On Investments GainLossOnInvestments	-4000	USD
CY2020Q4	us-gaap	Gain Loss On Investments GainLossOnInvestments	295000	USD
CY2020	us-gaap	Gain Loss On Investments GainLossOnInvestments	930000	USD
CY2020Q1	us-gaap	Other Income OtherIncome	900000	USD
CY2020Q2	us-gaap	Other Income OtherIncome	1223000	USD
CY2020Q3	us-gaap	Other Income OtherIncome	648000	USD
CY2020Q4	us-gaap	Other Income OtherIncome	513000	USD
CY2020	us-gaap	Other Income OtherIncome	3284000	USD
CY2020Q1	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	5697000	USD
CY2020Q2	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	34334000	USD
CY2020Q3	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	15667000	USD
CY2020Q4	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	3549000	USD
CY2020	us-gaap	Incurred Claims Property Casualty And Liability IncurredClaimsPropertyCasualtyAndLiability	59247000	USD
CY2020Q1	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	32277000	USD
CY2020Q2	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	30370000	USD
CY2020Q3	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	33969000	USD
CY2020Q4	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	34994000	USD
CY2020	us-gaap	Other Cost And Expense Operating OtherCostAndExpenseOperating	131610000	USD
CY2020Q1	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	734000	USD
CY2020Q2	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	1090000	USD
CY2020Q3	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	557000	USD
CY2020Q4	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	459000	USD
CY2020	us-gaap	Other Nonoperating Expense OtherNonoperatingExpense	2840000	USD
CY2020Q1	us-gaap	Interest Expense InterestExpense	2744000	USD
CY2020Q2	us-gaap	Interest Expense InterestExpense	5941000	USD
CY2020Q3	us-gaap	Interest Expense InterestExpense	7796000	USD
CY2020Q4	us-gaap	Interest Expense InterestExpense	7906000	USD
CY2020	us-gaap	Interest Expense InterestExpense	24387000	USD
CY2020Q1	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	5959000	USD
CY2020Q2	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	-1236000	USD
CY2020Q3	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	-437000	USD
CY2020Q4	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	-1379000	USD
CY2020	nmih	Gain Losson Changein Fair Valueof Warrant Liability GainLossonChangeinFairValueofWarrantLiability	2907000	USD
CY2020Q1	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	72156000	USD
CY2020Q2	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	34977000	USD
CY2020Q3	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	49357000	USD
CY2020Q4	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	61616000	USD
CY2020	us-gaap	Income Loss From Continuing Operations Before Income Taxes Extraordinary Items Noncontrolling Interest IncomeLossFromContinuingOperationsBeforeIncomeTaxesExtraordinaryItemsNoncontrollingInterest	218106000	USD
CY2020Q1	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	13885000	USD
CY2020Q2	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	8129000	USD
CY2020Q3	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	11178000	USD
CY2020Q4	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	13348000	USD
CY2020	us-gaap	Income Tax Expense Benefit IncomeTaxExpenseBenefit	46540000	USD
CY2020Q1	us-gaap	Net Income Loss NetIncomeLoss	58271000	USD
CY2020Q2	us-gaap	Net Income Loss NetIncomeLoss	26848000	USD
CY2020Q3	us-gaap	Net Income Loss NetIncomeLoss	38179000	USD
CY2020Q4	us-gaap	Net Income Loss NetIncomeLoss	48268000	USD
CY2020	us-gaap	Net Income Loss NetIncomeLoss	171566000	USD
CY2020Q1	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.85
CY2020Q2	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.36
CY2020Q3	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.45
CY2020Q4	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	0.57
CY2020	us-gaap	Earnings Per Share Basic EarningsPerShareBasic	2.20
CY2020Q1	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.74
CY2020Q2	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.36
CY2020Q3	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.45
CY2020Q4	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	0.56
CY2020	us-gaap	Earnings Per Share Diluted EarningsPerShareDiluted	2.13
CY2020Q1	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	68563000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	73617000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84805000	shares
CY2020Q4	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	84956000	shares
CY2020	us-gaap	Weighted Average Number Of Shares Outstanding Basic WeightedAverageNumberOfSharesOutstandingBasic	78023000	shares
CY2020Q1	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	70401000	shares
CY2020Q2	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	74174000	shares
CY2020Q3	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	85599000	shares
CY2020Q4	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	86250000	shares
CY2020	us-gaap	Weighted Average Number Of Diluted Shares Outstanding WeightedAverageNumberOfDilutedSharesOutstanding	79263000	shares
CY2021Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Cost SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCost	2078773000	USD
CY2021Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Fair Value SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesFairValue	2085931000	USD
CY2021Q4	us-gaap	Summary Of Investments Other Than Investments In Related Parties Carrying Amount SummaryOfInvestmentsOtherThanInvestmentsInRelatedPartiesCarryingAmount	2085931000	USD
CY2021Q4	us-gaap	Common Stock Value Outstanding CommonStockValueOutstanding	858000	USD
CY2021Q4	us-gaap	Additional Paid In Capital AdditionalPaidInCapital	955302000	USD
CY2021Q4	us-gaap	Accumulated Other Comprehensive Income Loss Net Of Tax AccumulatedOtherComprehensiveIncomeLossNetOfTax	1485000	USD
CY2021Q4	us-gaap	Retained Earnings Accumulated Deficit RetainedEarningsAccumulatedDeficit	608141000	USD
CY2021Q4	us-gaap	Stockholders Equity StockholdersEquity	1565786000	USD
CY2021	us-gaap	Net Income Loss NetIncomeLoss	231130000	USD
CY2021	us-gaap	Proceeds From Issuance Of Shares Under Incentive And Share Based Compensation Plans Including Stock Options ProceedsFromIssuanceOfSharesUnderIncentiveAndShareBasedCompensationPlansIncludingStockOptions	4201000	USD
CY2021	us-gaap	Proceeds From Warrant Exercises ProceedsFromWarrantExercises	503000	USD
CY2021	us-gaap	Payments Related To Tax Withholding For Share Based Compensation PaymentsRelatedToTaxWithholdingForShareBasedCompensation	5426000	USD
CY2021	us-gaap	Payments Of Debt Issuance Costs PaymentsOfDebtIssuanceCosts	1108000	USD
CY2021Q4	nmih	Ordinary Dividends Restrictionwith Regardsto Capital Surplus Next Fiscal Year OrdinaryDividendsRestrictionwithRegardstoCapitalSurplusNextFiscalYear	34900000	USD

Files In Submission

Name	View Source	Status
0001547903-22-000060-index-headers.html	Edgar Link	pending
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$NMIH
NMI Holdings, Inc. Stock $nmih

2021 Q4 Form 10-K Financial Statement

#000154790322000060 Filed on February 16, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NMIH NMI Holdings, Inc. Stock $nmih

2021 Q4 Form 10-K Financial Statement

#000154790322000060 Filed on February 16, 2022

Income Statement

Balance Sheet

Cashflow Statement

Facts In Submission

Files In Submission

$NMIH
NMI Holdings, Inc. Stock $nmih