Name:	ambc_BalanceOfRmbsSubrogationRecoveriesNetOfReinsurance
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Domestic Public Finance Losses

No definition available.

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

No definition available.

Name:	ambc_EstimatedFuturePremiumPaymentsWeightedAverageDiscountedRate
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Insurance [Line Items]

No definition available.

Name:	ambc_InsuranceLineItems
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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
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March 2021 Ameerican Rescue Plan Amount

No definition available.

Name:	ambc_March2021AmeericanRescuePlanAmount
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Possible Increase in Domestic Public Finance Loss Reserves

No definition available.

Name:	ambc_PossibleIncreaseinDomesticPublicFinanceLossReserves
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Public Finance Puerto Rico Net Par Outstanding

No definition available.

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

No definition available.

Name:	ambc_StockholdersEquityAfterPossibleInabilityToRealizeRWSubrogationRecoveries
Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
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Stockholders Equity After Possible Increase in Domestic Public Finance Loss Reserves

No definition available.

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Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
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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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The carrying amount as of the balance sheet date of the known and estimated amounts owed to insurers under reinsurance treaties or other arrangements.

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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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