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Financial Guarantee Insurance Contracts - Summary of Rollforward of RMBS Subrogation, by Estimation Approach (Detail) $ in Millions | Dec. 31, 2021 USD ($)
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Subrogation By Estimation Approach [Roll Forward] |
Discounted RMBS subrogation (gross of reinsurance), beginning balance | $ 1,751
Changes recognized |
Discounted RMBS subrogation (gross of reinsurance), ending balance | $ 1,730

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- Definition Changes Recognized in Residential Mortgage Backed Security [Abstract] + References No definition available. + Details
Name: | ambc_ChangesRecognizedInResidentialMortgageBackedSecurityAbstract
Namespace Prefix: | ambc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition This element represents the reduction to gross claim liability for subrogation on insured RMBS financial obligations with credit deterioration. + References No definition available. + Details
Name: | ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation
Namespace Prefix: | ambc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Subrogation By Estimation Approach [Roll Forward] + References No definition available. + Details
Name: | ambc_SubrogationByEstimationApproachRollForward
Namespace Prefix: | ambc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration