XML 38 R76.htm IDEA: XBRL DOCUMENT v2.4.1.9

Fair Value Of Financial Instruments (Realized And Unrealized Gains And Losses Included In Earnings Pertaining To Level 3 Assets And Liabilities) (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	$ 903us-gaap_UnrealizedGainLossOnDerivatives	$ 1,777us-gaap_UnrealizedGainLossOnDerivatives	$ 1,870us-gaap_UnrealizedGainLossOnDerivatives
Net gains (losses) on financial instruments at fair value and foreign exchange	78mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange	69mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange	55mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange
Net investment losses related to other-than-temporary impairments	(15)us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet		(105)us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet
Fair Value Inputs Level 3 [Member] | Total Gains Losses Included In Earnings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	903us-gaap_UnrealizedGainLossOnDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	1,778us-gaap_UnrealizedGainLossOnDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	1,869us-gaap_UnrealizedGainLossOnDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Realized gains and other settlements on insured derivatives	(445)mbi_RealizedGainsLossesAndOtherSettlementsOnInsuredDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	(1,548)mbi_RealizedGainsLossesAndOtherSettlementsOnInsuredDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	(407)mbi_RealizedGainsLossesAndOtherSettlementsOnInsuredDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Net gains (losses) on financial instruments at fair value and foreign exchange	18mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	(37)mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	13mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Net investment losses related to other-than-temporary impairments			(68)us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Total revenues	444us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	353us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	1,031us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Fair Value Inputs Level 3 [Member] | Change In Unrealized Gains Losses For Period Included In Earnings For Assets And Liabilities Still Held [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Unrealized gains (losses) on insured derivatives	20us-gaap_UnrealizedGainLossOnDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	(87)us-gaap_UnrealizedGainLossOnDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	927us-gaap_UnrealizedGainLossOnDerivatives / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Net gains (losses) on financial instruments at fair value and foreign exchange	12mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	(12)mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	(6)mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Total revenues	52us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	161us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member	650us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Total Gains Losses Included In Earnings [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	(32)mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember	160mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember	(376)mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_TotalGainsLossesIncludedInEarningsMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Change In Unrealized Gains Losses For Period Included In Earnings For Assets And Liabilities Still Held [Member]
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Net gains (losses) on financial instruments at fair value and foreign exchange	$ 20mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember	$ 260mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember	$ (271)mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange / mbi_FairValueByConsolidatedStatementsOfOperationsAxis = mbi_ChangeInUnrealizedGainsLossesForPeriodIncludedInEarningsForAssetsAndLiabilitiesStillHeldMember / us-gaap_FairValueByFairValueHierarchyLevelAxis = us-gaap_FairValueInputsLevel3Member / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember

X

- Definition

Change in the fair value of and realized gains and losses on sale of financial instruments and foreign exchange included in earnings.

+ References

No definition available.

+ Details

Name:	mbi_NetGainsLossesOnFinancialInstrumentsAtFairValueAndForeignExchange
Namespace Prefix:	mbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

Realized gains and losses and recognized premiums and fees related to insurance policies on derivatives included in earnings.

+ References

No definition available.

+ Details

Name:	mbi_RealizedGainsLossesAndOtherSettlementsOnInsuredDerivatives
Namespace Prefix:	mbi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_FairValueAssetsAndLiabilitiesMeasuredOnRecurringAndNonrecurringBasisLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of realized and unrealized gain (loss) included in earnings, which have arisen from the use of significant unobservable inputs (level 3) to measure fair value of assets, liabilities, and financial instruments classified in shareholders' equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasuredOnRecurringBasisGainLossIncludedInEarnings
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Definition

The amount of other than temporary impairment (OTTI) losses on equity securities, OTTI related to credit losses on debt securities, and OTTI losses on debt securities when the entity intends to sell the securities or it is more likely than not that the entity will be required to sell the securities before recovery of its amortized cost basis. Additionally, this item includes OTTI losses recognized during the period on investments accounted for under the cost method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 320

-SubTopic 10

-Section 50

-Paragraph 8B

-URI http://asc.fasb.org/extlink&oid=27724398&loc=SL6284393-111563

+ Details

Name:	us-gaap_OtherThanTemporaryImpairmentLossesInvestmentsPortionRecognizedInEarningsNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

The net change in the difference between the fair value and the carrying value, or in the comparative fair values, of derivative instruments, including options, swaps, futures, and forward contracts, held at each balance sheet date, that was included in earnings for the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

+ Details

Name:	us-gaap_UnrealizedGainLossOnDerivatives
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: