Name:	ago_GainContingencyAllegationsPaymentForTerminationofCreditDerivativeTransactionsOwedbyDefendanttoPlaintiffAsPerCalculationofPlaintiff
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Represents the amount of payment on the termination of credit derivatives transactions which the plaintiff owes to defendant as per the calculation of defendant.

No definition available.

Name:	ago_GainContingencyAllegationsPaymentForTerminationofCreditDerivativeTransactionsOwedbyPlaintifftoDefendantAsPerCalculationofDefendant
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Represents the amount of insured contractual payments (principal and interest) outstanding on the underlying insured obligations for financial guaranty contracts, net of ceded contracts.

No definition available.

Name:	ago_InsuredFinancialObligationsInsuredContractualPaymentsOutstandingNet
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Data Type:	xbrli:monetaryItemType
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Represents the number of credit derivative transactions which the entity has improperly terminated as per the allegations of the plaintiff.

No definition available.

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Namespace Prefix:	ago_
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Represents the number of credit derivative transactions which the entity has improperly calculated termination payment as per the allegations of the plaintiff.

No definition available.

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Namespace Prefix:	ago_
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Number Of Insured Financial Obligations Sold

No definition available.

Name:	ago_NumberOfInsuredFinancialObligationsSold
Namespace Prefix:	ago_
Data Type:	xbrli:integerItemType
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Period Type:	duration

The amount or range of possible amounts of gain that could be realized upon the resolution of a contingency.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 30
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6397426&loc=d3e17499-108355

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Data Type:	xbrli:monetaryItemType
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_LossContingenciesLineItems
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Period Type:	duration

The cash inflow associated with the sale of insurance policy investment assets during the period.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3179-108585

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