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v2.4.1.9

Common and Preferred Stock (Narrative) (Detail) (USD $) In Millions, except Share data, unless otherwise specified | 12 Months Ended | 0 Months Ended | 95 Months Ended | 0 Months Ended |
--- | --- | --- | --- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013 | May 06, 2013 | Feb. 01, 2007 | Dec. 31, 2014 | Nov. 05, 2014 | Aug. 05, 2013 | Dec. 31, 2008
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Fair value of warrants | $ 28 us-gaap_WarrantsAndRightsOutstanding | $ 59 us-gaap_WarrantsAndRightsOutstanding |  |  | $ 28 us-gaap_WarrantsAndRightsOutstanding |  |  |
Treasury stock value acquired cost method | 35 us-gaap_TreasuryStockValueAcquiredCostMethod | 7 us-gaap_TreasuryStockValueAcquiredCostMethod |  |  |  |  |  |
Preferred stock shares issued | 0 us-gaap_PreferredStockSharesIssued | 0 us-gaap_PreferredStockSharesIssued |  |  | 0 us-gaap_PreferredStockSharesIssued |  |  |
Preferred stock shares outstanding | 0 us-gaap_PreferredStockSharesOutstanding | 0 us-gaap_PreferredStockSharesOutstanding |  |  | 0 us-gaap_PreferredStockSharesOutstanding |  |  |
Preferred Stock Par Or Stated Value Per Share | $ 1 us-gaap_PreferredStockParOrStatedValuePerShare | $ 1 us-gaap_PreferredStockParOrStatedValuePerShare |  |  | $ 1 us-gaap_PreferredStockParOrStatedValuePerShare |  |  |
Blue Ridge [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Warrants outstanding |  |  | 9,940,000 us-gaap_ClassOfWarrantOrRightOutstanding / dei_LegalEntityAxis = mbi_BlueRidgeMember |  |  |  |  |
Warrant exercise price |  |  | 9.59 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / dei_LegalEntityAxis = mbi_BlueRidgeMember |  |  |  |  |
Warrant Term |  |  | 5 years |  |  |  |  |
Preferred Stock [Member] | MBIA Insurance Corporation [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Shares repurchased under share repurchase program, average price per share | $ 10,900.00 us-gaap_TreasuryStockAcquiredAverageCostPerShare / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  |  |  |  |
Preferred stock shares issued | 2,759 us-gaap_PreferredStockSharesIssued / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  | 2,759 us-gaap_PreferredStockSharesIssued / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |
Preferred stock repurchased during period shares | 1,444 us-gaap_StockRepurchasedDuringPeriodShares / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  |  |  |  |
Preferred stock, carrying value issued and outstanding | 28 us-gaap_PreferredStockValueOutstanding / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  | 28 us-gaap_PreferredStockValueOutstanding / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |
Face value of repurchased preferred stock | 10.90%mbi_PercentageOfFaceValueOfRepurchasedPreferredStock / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  |  |  |  |
Preferred Stock Par Or Stated Value Per Share | $ 1,000 us-gaap_PreferredStockParOrStatedValuePerShare / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  | $ 1,000 us-gaap_PreferredStockParOrStatedValuePerShare / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |
Preferred stock liquidation preference | $ 100,000 us-gaap_PreferredStockLiquidationPreference / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |  | $ 100,000 us-gaap_PreferredStockLiquidationPreference / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = us-gaap_PreferredStockMember |  |  |
Dividend rate on preferred stock determined rate | LIBOR plus 200 basis points |  |  |  |  |  |  |
2007 Repurchase Authorization [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Authorized repurchase of common stock, value |  |  |  | 1,000 us-gaap_StockRepurchaseProgramAuthorizedAmount / us-gaap_StatementClassOfStockAxis = mbi_TwoThousandAndSevenRepurchaseAuthorizationMember |  |  |  |
Treasury stock shares acquired | 2,100,000 us-gaap_TreasuryStockSharesAcquired / us-gaap_StatementClassOfStockAxis = mbi_TwoThousandAndSevenRepurchaseAuthorizationMember |  |  |  | 58,800,000 us-gaap_TreasuryStockSharesAcquired / us-gaap_StatementClassOfStockAxis = mbi_TwoThousandAndSevenRepurchaseAuthorizationMember |  |  |
Shares repurchased under share repurchase program, average price per share |  |  |  |  | $ 17.02 us-gaap_TreasuryStockAcquiredAverageCostPerShare / us-gaap_StatementClassOfStockAxis = mbi_TwoThousandAndSevenRepurchaseAuthorizationMember |  |  |
2014 Repurchase Authorization [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Authorized repurchase of common stock, value |  |  |  |  |  | $ 200 us-gaap_StockRepurchaseProgramAuthorizedAmount / us-gaap_StatementClassOfStockAxis = mbi_TwothousandfourteenrepurchaseauthorizationMember |  |
Treasury stock shares acquired | 1,200,000 us-gaap_TreasuryStockSharesAcquired / us-gaap_StatementClassOfStockAxis = mbi_TwothousandfourteenrepurchaseauthorizationMember |  |  |  |  |  |  |
Shares repurchased under share repurchase program, average price per share | $ 9.44 us-gaap_TreasuryStockAcquiredAverageCostPerShare / us-gaap_StatementClassOfStockAxis = mbi_TwothousandfourteenrepurchaseauthorizationMember |  |  |  |  |  |  |
Unaffiliated Investors [Member] | MBIA Insurance Corporation [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Preferred stock shares outstanding | 1,315 us-gaap_PreferredStockSharesOutstanding / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = mbi_UnaffiliatedInvestorsMember |  |  |  | 1,315 us-gaap_PreferredStockSharesOutstanding / dei_LegalEntityAxis = mbi_InsuranceCorporationMember / us-gaap_StatementClassOfStockAxis = mbi_UnaffiliatedInvestorsMember |  |  |
Long-Term Incentive Plan [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Treasury stock shares acquired | 529,246 us-gaap_TreasuryStockSharesAcquired / us-gaap_AwardTypeAxis = mbi_LongTermIncentivePlanMember | 392,056 us-gaap_TreasuryStockSharesAcquired / us-gaap_AwardTypeAxis = mbi_LongTermIncentivePlanMember |  |  |  |  |  |
Warrant [Member] | Warburg Pincus [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Warrants outstanding |  |  |  |  |  |  | 11,800,000 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = us-gaap_WarrantMember / dei_LegalEntityAxis = mbi_WarburgPincusMember | 11,500,000 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = us-gaap_WarrantMember / dei_LegalEntityAxis = mbi_WarburgPincusMember
Warrant exercise price |  |  |  |  |  |  | 29.44 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = us-gaap_WarrantMember / dei_LegalEntityAxis = mbi_WarburgPincusMember | 30.25 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = us-gaap_WarrantMember / dei_LegalEntityAxis = mbi_WarburgPincusMember
B Warrants [Member] | Warburg Pincus [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Warrants outstanding |  |  |  |  |  |  | 10,100,000 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember | 9,800,000 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember
Warrant exercise price |  |  |  |  |  |  | 29.44 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember | 30.25 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember
B2 Warrants [Member] | Warburg Pincus [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Warrants outstanding |  |  |  |  |  |  | 4,004,945 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBTwoWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember | 4,000,000 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBTwoWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember
Warrant exercise price |  |  |  |  |  |  | 16.18 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBTwoWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember | 16.2 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = mbi_ClassBTwoWarrantsMember / dei_LegalEntityAxis = mbi_WarburgPincusMember
Grossup Warrant [Member] | Warburg Pincus [Member] |  |  |  |  |  |  |  |
Class of Stock [Line Items] |  |  |  |  |  |  |  |
Warrants outstanding |  |  |  |  |  |  | 1,910,000 us-gaap_ClassOfWarrantOrRightOutstanding / us-gaap_ClassOfWarrantOrRightAxis = mbi_GrossupWarrantMember / dei_LegalEntityAxis = mbi_WarburgPincusMember |
Warrant exercise price |  |  |  |  |  |  | 9.59 us-gaap_ClassOfWarrantOrRightExercisePriceOfWarrantsOrRights / us-gaap_ClassOfWarrantOrRightAxis = mbi_GrossupWarrantMember / dei_LegalEntityAxis = mbi_WarburgPincusMember |
Warrant Term |  |  |  |  |  |  | 5 years |

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