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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:	abk_EstimatedFuturePremiumPaymentsWeightedAverageDiscountedRate
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

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Namespace Prefix:	abk_
Data Type:	xbrli:stringItemType
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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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesBaseFee
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesBaseReferenceObligationSpread
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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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Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesFullRelativeChangeRatio
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesHypotheticalIncrementalFee
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesHypotheticalIncrementalFeeWithCreditDeterioration
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesRemainingLife
Namespace Prefix:	abk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesRevisedHypotheticalFee
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesRevisedHypotheticalFeeWithCreditDownGrade
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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.

Name:	abk_FairValueMeasurementProcessDescriptionForCreditDerivativesRevisedRelativeChangeRatio
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
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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:	abk_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Percentage of credit derivative gross par outstanding using internally estimated reference obligation prices in determination of fair value.

No definition available.

Name:	abk_PercentageOfCreditDerivativeGrossParOutstandingUsingInternallyEstimatedReferenceObligationPricesInDeterminationOfFairValue
Namespace Prefix:	abk_
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:	abk_
Data Type:	num:percentItemType
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Period Type:	duration

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:	abk_
Data Type:	num:percentItemType
Balance Type:	na
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:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

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

No definition available.

Name:	abk_PercentageOfCreditValueAdjustment
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Investment portfolio valued using dealer quotes.

No definition available.

Name:	abk_PercentageOfInvestmentPortfolioValuedUsingDealerQuotes
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percentage of investment portfolio valued using external pricing services.

No definition available.

Name:	abk_PercentageOfInvestmentPortfolioValuedUsingExternalPricingServices
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percentage of investment portfolio valued using internal valuation models.

No definition available.

Name:	abk_PercentageOfInvestmentPortfolioValuedUsingInternalValuationModels
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

The weighted average discount rate used to determine the fair value of call options to repurchase surplus notes.

No definition available.

Name:	abk_WeightedAverageDiscountRateUsedToFairValueOptionsToRepurchaseSurplusNotes
Namespace Prefix:	abk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

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

No definition available.

Name:	us-gaap_DerivativeCreditRiskValuationAdjustmentDerivativeLiabilities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
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Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 205G

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 44C

-Subparagraph a

-Clause 1

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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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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=7578670&loc=d3e19207-110258

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

Aggregate notional amount of credit risk derivatives.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959