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Special Purpose Entities, Including Variable Interest Entities - Summary of Carrying Amount of Assets, Liabilities and Maximum Exposure to Loss of Ambac's Variable Interests in Non-Consolidated Variable Interest Entities (Detail) (Variable Interest Entity [Member], Successor [Member], USD $) In Thousands, unless otherwise specified | Dec. 31, 2014 | Dec. 31, 2013
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Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | $ 61,258,561 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount | $ 74,292,628 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Insurance Assets | 1,767,771 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets | 1,728,422 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets
Insurance Liabilities | 5,076,654 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities | 6,662,385 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities
Derivative Liabilities | (186,401)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities | (161,408)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities
Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 29,619,557 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 38,559,770 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 1,309,997 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 1,196,903 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 4,543,462 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 6,058,046 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Derivative Liabilities | (164,266)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | (134,296)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Global Public Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 31,639,004 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 35,732,858 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 457,774 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 531,519 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 533,192 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 604,339 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Derivative Liabilities | (22,135)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | (27,112)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalPublicFinanceMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Collateralized Debt Obligations [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 1,386,100 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 2,317,612 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 345 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 3,867 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 4,000 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 7,119 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Derivative Liabilities | (145,565)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | (102,704)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_CollateralizedDebtObligationsMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Residential Mortgage-Backed Securities [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 16,202,408 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 19,231,335 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 1,011,888 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 581,498 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 2,924,987 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 3,890,937 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_ResidentialMortgageBackedSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Other Consumer Asset-Backed [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 5,109,776 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 5,425,583 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 65,204 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 68,511 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 885,572 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 992,177 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Derivative Liabilities | (36,877)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | (39,916)ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherConsumerAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Other Commercial Asset-Backed [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 3,119,891 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 7,237,953 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 135,215 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 429,559 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 128,988 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 559,600 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Derivative Liabilities | 0 ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 0 ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = ambc_OtherCommercialAssetBackedMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Other [Member] | Global Structured Finance [Member] |  |
Variable Interest Entities [Line Items] |  |
Maximum Exposure To Loss | 3,801,382 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 4,347,287 us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Assets | 97,345 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 113,468 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Insurance Liabilities | 599,915 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | 608,213 ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember
Derivative Liabilities | $ 18,176 ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember | $ 8,324 ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities / us-gaap_DebtSecurityAxis = ambc_GlobalStructuredFinanceMember / us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis = us-gaap_OtherDebtSecuritiesMember / us-gaap_StatementScenarioAxis = us-gaap_SuccessorMember / us-gaap_VariableInterestEntitiesByClassificationOfEntityAxis = us-gaap_VariableInterestEntityPrimaryBeneficiaryMember

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- Definition The net carrying amount of derivative assets or liabilities in the reporting entity's statement of financial position that relate to the entity's variable interests in Variable Interest Entities (VIEs) where the VIEs are not consolidated. + References No definition available. + Details
Name: | ambc_VariableInterestEntityNonconsolidatedCarryingAmountDerivativeNetAssetsOrLiabilities
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition The carrying amount of insurance assets in the reporting entity's statement of financial position that relate to the entity's variable interests in Variable Interest Entities (VIEs) where the VIEs are not consolidated. + References No definition available. + Details
Name: | ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceAssets
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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- Definition The carrying amount of insurance liabilities in the reporting entity's statement of financial position that relate to the entity's variable interests in Variable Interest Entities (VIEs) where the VIEs are not consolidated. + References No definition available. + Details
Name: | ambc_VariableInterestEntityNonconsolidatedCarryingAmountInsuranceLiabilities
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph b -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5728-111685 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=28200181&loc=d3e5747-111685 + Details
Name: | us-gaap_VariableInterestEntityEntityMaximumLossExposureAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Details
Name: | us-gaap_VariableInterestEntityLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration