Name:	ambc_DerivativesCreditRiskValuationAdjustmentDerivativeLiabilitiesOtherThanCreditDerivatives
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Data Type:	xbrli:monetaryItemType
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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
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Hypothetical base fee received on a credit derivative contract used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Data Type:	num:percentItemType
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Hypothetical base reference obligation spread used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Data Type:	num:percentItemType
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Hypothetical base relative change ratio for a credit derivative contract used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Data Type:	num:percentItemType
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Full relative change ratio comparable to certain default used in the description of the valuation processes in place for fair value measurement of credit derivative.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Hypothetical incremental credit derivative fee used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Hypothetical incremental credit derivative fee given a certain credit downgrade used in the description of the valuation processes in place for fair value measurement of credit derivative.

No definition available.

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Data Type:	num:percentItemType
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Hypothetical remaining contract life used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

Name:	ambc_FairValueMeasurementProcessDescriptionForCreditDerivativesRemainingLife
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Data Type:	xbrli:durationItemType
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Hypothetical revised fee required on credit derivative contract used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Hypothetical revised fee required on credit derivative given a certain credit downgrade used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Data Type:	num:percentItemType
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Hypothetical revised reference obligation spread (second example) used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Data Type:	num:percentItemType
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Hypothetical revised relative change ratio used in the description of the valuation processes in place for fair value measurement of credit derivatives.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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- Details

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Data Type:	xbrli:stringItemType
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Fair Value of consolidated VIE debt obligations valued using unobservable inputs by asset class

No definition available.

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Data Type:	xbrli:monetaryItemType
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Fair value of investments in securities valued using unobservable inputs by asset class.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	xbrli:monetaryItemType
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Percentage of credit derivative gross par outstanding using internally estimated reference obligation prices in determination of fair value.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Period Type:	duration

Percentage of credit derivative liability using internally estimated reference obligation prices in determination of fair value.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Percentage of credit derivatives gross par outstanding using third party reference obligation quotes in determination of fair value.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Period Type:	duration

Percentage of credit derivatives liability using third party reference obligation quotes ion determination of fair value.

No definition available.

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Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Period Type:	duration

Credit valuation adjustment (CVA) as a percentage of the credit derivative liability calculated excluding the CVA.

No definition available.

Name:	ambc_PercentageOfCreditValueAdjustment
Namespace Prefix:	ambc_
Data Type:	num:percentItemType
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Period Type:	instant

Investment portfolio valued using dealer quotes.

No definition available.

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

Percentage of investment portfolio valued using external pricing services.

No definition available.

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

Percentage of investment portfolio valued using internal valuation models.

No definition available.

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

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 12

-Section 13

-Sentence Column B

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Amount of credit risk valuation adjustment to derivative liabilities to properly reflect the credit quality of the entity.

No definition available.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Fair value before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 55

-Paragraph 7

-URI http://asc.fasb.org/extlink&oid=28370219&loc=SL20226000-175313

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 20

-Section 50

-Paragraph 3

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=20225523&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (a),(c)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Ratio of an entity's operating income net of tax to its revenue, used as an input to measure fair value.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bbb)

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