Name:	ambc_BalanceOfRmbsSubrogationRecoveriesNetOfReinsurance
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

CCDA Share of Contingent Value Instrument

No definition available.

Name:	ambc_CCDAShareOfContingentValueInstrument
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Clawback CVI Lifetime Nominal Cap

No definition available.

Name:	ambc_ClawbackCVILifetimeNominalCap
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Weighted average discounted rate of estimated future premium payments to be paid by the VIEs.

No definition available.

Name:	ambc_EstimatedFuturePremiumPaymentsWeightedAverageDiscountedRate
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Insurance [Line Items]

No definition available.

Name:	ambc_InsuranceLineItems
Namespace Prefix:	ambc_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The known and estimated amount recoverable as of the balance sheet date from reinsurers for claims expected to be paid or incurred by the ceding insurer.

No definition available.

Name:	ambc_LossReservesCededToReinsurers
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

March 2021 Ameerican Rescue Plan Amount

No definition available.

Name:	ambc_March2021AmeericanRescuePlanAmount
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Nominal Cap of Allowed PRIFA Under Seventh Amended POA

No definition available.

Name:	ambc_NominalCapOfAllowedPRIFAUnderSeventhAmendedPOA
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

PRHTA Share of Contingent Value Instrument

No definition available.

Name:	ambc_PRHTAShareOfContingentValueInstrument
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

PRIFA Trust Funded Share of Clawback CVI

No definition available.

Name:	ambc_PRIFATrustFundedShareOfClawbackCVI
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Possible Increase in Domestic Public Finance Loss Reserves

No definition available.

Name:	ambc_PossibleIncreaseinDomesticPublicFinanceLossReserves
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Public Finance Puerto Rico Net Par Outstanding

No definition available.

Name:	ambc_PublicFinancePuertoRicoNetParOutstanding
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Reinsurance Recoverable Credit Exposure

No definition available.

Name:	ambc_ReinsuranceRecoverableCreditExposure
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

This element represents the reduction to gross claim liability for subrogation on insured RMBS financial obligations with credit deterioration.

No definition available.

Name:	ambc_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityRmbsSubrogation
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Seventh Amended POA Proposed Debt Restructure Amount

No definition available.

Name:	ambc_SeventhAmendedPOAProposedDebtRestructureAmount
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Seventh Amended POA Proposed Pension Obligation Restructure Amount

No definition available.

Name:	ambc_SeventhAmendedPOAProposedPensionObligationRestructureAmount
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Stockholders Equity After Possible Inability to Realize R&W Subrogation Recoveries

No definition available.

Name:	ambc_StockholdersEquityAfterPossibleInabilityToRealizeRWSubrogationRecoveries
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Stockholders Equity After Possible Increase in Domestic Public Finance Loss Reserves

No definition available.

Name:	ambc_StockholdersEquityAfterPossibleIncreaseinDomesticPublicFinanceLossReserves
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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This element represents the amount of premium revenue on financial guarantee insurance contracts recognized during the period that was accelerated for revenue recognition purposes.

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This element represents the weighted average risk free rate used to discount the claim liability related to financial guarantee insurance contracts.

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Amount of the premium receivable for financial guarantee insurance contracts reported in the statement of financial position. This element primarily would consist of those financial guarantee insurance contracts which premiums are to be collected over the contract period, but may, on occasion, include premiums which are to be collected in full at inception, but which straddle a financial reporting period.

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Weighted average period over which premium receivable for financial guarantee insurance contracts is collected where premium is received over the contract period, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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The carrying value as of the balance sheet date of the estimated valuation allowance to reduce gross premiums receivable to net realizable value.

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Amount of reduction of provision for policy benefits and costs incurred for policies ceded.

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Period Type:	duration

The carrying amount as of the balance sheet date of the known and estimated amounts owed to insurers under reinsurance treaties or other arrangements.

No definition available.

Name:	us-gaap_ReinsurancePayable
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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