Liability as of the balance sheet date for amounts representing estimated cost of settling unpaid claims under the terms of the underlying insurance policies, less estimated reinsurance recoveries on such claims, for contracts ceded by the entity.

Name:	ago_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseCeded
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_LiabilityForUnpaidClaimsAndClaimsAdjustmentExpenseDirectAssumed
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the entity's estimate of the present value of future claim payments, net of reinsurance and net of salvage and subrogation which includes the present value benefit of estimated recoveries for breaches of R&W, including the effect of consolidating VIEs.

+ Details

Name:	ago_NetExpectedLossToBePaid
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_NetExpectedLossToBePaidExcludingVIEs
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the estimate of the present value of future claim payments related to consolidating of financial guaranty VIEs, net of reinsurance and net of salvage and subrogation which includes the present value benefit of estimated recoveries for breaches of R&W.

+ Details

Name:	ago_NetExpectedLossToBePaidForConsolidatingVIEs
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the reserve for losses and loss adjustment expenses, net of reinsurance recoverable on unpaid losses and net of salvage and subrogation recoverable.

+ Details

Name:	ago_ReserveForLossesAndLossAdjustmentExpensesNetOfReinsuranceAndSalvageAndSubrogationRecoveries
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the effect on reserve for losses and loss adjustment expenses, net of reinsurance recoverable on unpaid losses and net of salvage and subrogation recoverable related to consolidating VIEs.

+ Details

Name:	ago_ReserveForLossesAndLossAdjustmentExpensesNetOfReinsuranceAndSalvageAndSubrogationRecoveriesAdjustmentForConsolidatingVIEs
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the reserve for losses and loss adjustment expenses, net of reinsurance recoverable on unpaid losses, net of salvage and subrogation recoverable and before adjusting for the effect of consolidating VIEs.

+ Details

Name:	ago_ReserveForLossesAndLossAdjustmentExpensesNetOfReinsuranceAndSalvageAndSubrogationRecoveriesBeforeVIEAdjustment
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the reserve for losses and loss adjustment expenses, net of reinsurance recoverable on unpaid losses, net of salvage and subrogation recoverable, for contracts ceded by the entity.

+ Details

Name:	ago_ReserveForLossesAndLossAdjustmentExpensesNetOfReinsuranceAndSalvageAndSubrogationRecoveriesCeded
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the reserve for losses and loss adjustment expenses, net of reinsurance recoverable on unpaid losses, net of salvage and subrogation recoverable, for contracts the entity has issued directly or assumed.

+ Details

Name:	ago_ReserveForLossesAndLossAdjustmentExpensesNetOfReinsuranceAndSalvageAndSubrogationRecoveriesDirectAssumed
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationExpectedCashFlowsAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the gross claim liability for financial guaranty insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts related to consolidating VIEs.

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiabilityBeforeVIEAdjustment
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsInterestAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the amount of insured contractual payments outstanding on the underlying insured obligations for financial guaranty insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts ceded by the entity.

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingGross
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of insured contractual payments outstanding attributable to interest accrued on the underlying insured obligations for financial guaranty insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts ceded by the entity.

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingNet
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipalAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the amount of insured contractual payments outstanding attributable to the principal of the underlying insured obligations for financial guaranty insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts ceded by the entity.

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipalGross
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipalNet
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Represents the number of issued and outstanding contracts for each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts ceded by the entity.

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstandingCeded
Namespace Prefix:	ago
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstandingGross
Namespace Prefix:	ago
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstandingNet
Namespace Prefix:	ago
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfRisksAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityGrossPotentialRecoveriesAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the gross potential recoveries against the gross claim liability for financial guaranty insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts related to consolidating VIEs.

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityGrossPotentialRecoveriesAdjustmentForConsolidatingVIEs
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityGrossPotentialRecoveriesBeforeVIEAdjustment
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityGrossPotentialRecoveriesCeded
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityGrossPotentialRecoveriesDirectAssumed
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityNetDiscountAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the net discount consisting of the difference between the discount related to the claim liability for and potential recoveries thereof related to financial guaranty insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts related to consolidating VIEs.

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityNetDiscountAdjustmentForConsolidatingVIE
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityNetDiscountBeforeVIEAdjustment
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityNetDiscountCeded
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReductionsOfGrossClaimLiabilityNetDiscountDirectAssumed
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationRemainingWeightedAverageContractPeriodAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the remaining weighted average contract period of financial guaranty insurance contracts for each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts ceded by the entity.

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationRemainingWeightedAverageContractPeriodCeded
Namespace Prefix:	ago
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

+ Details

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Namespace Prefix:	ago
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationRemainingWeightedAverageContractPeriodNet
Namespace Prefix:	ago
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationReservesSalvageAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenueAbstract
Namespace Prefix:	ago
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the amount of unearned premium revenue, reported on or included in the statement of financial position, related to financial guarantee insurance contracts and presented in the schedule of insured financial obligations with credit deterioration in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts ceded by the entity.

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenueCeded
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

This element represents the amount of unearned premium revenue, reported on or included in the statement of financial position, related to financial guaranty insurance contracts and presented in the schedule of insured financial obligations with credit deterioration in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guaranty insurance contracts the entity has issued directly or assumed.

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenueDirectAssumed
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenueNet
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

+ Details

Name:	ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationStatementOfFinancialPositionUnearnedPremiumRevenueOfConsolidatingVIE
Namespace Prefix:	ago
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the gross claim liability for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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.

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-Name Statement of Financial Accounting Standard (FAS)
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-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 944
-SubTopic 40
-Section 55
-Paragraph 32
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-SubTopic 40
-Section 50
-Paragraph 9
-Subparagraph (a)(5)(iv)
-URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292

+ Details

Name:	us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationGrossClaimLiability
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of insured contractual payments outstanding on the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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.

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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Topic 944
-SubTopic 40
-Section 55
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6933462&loc=SL5751133-161288

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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Name:	us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingAbstract
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- Definition

This element represents the amount of insured contractual payments outstanding attributable to interest accrued on the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
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-Section Appendix A
-Paragraph A13
-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
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 40
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-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6933462&loc=SL5751133-161288

+ Details

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Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of insured contractual payments outstanding attributable to the principal of the underlying insured obligations for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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
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-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
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-SubTopic 40
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-Paragraph 32
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+ Details

Name:	us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipal
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNetClaimLiabilityAbstract
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents the number of issued and outstanding contracts for each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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)
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-Subparagraph a(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
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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-SubTopic 40
-Section 50
-Paragraph 9
-Subparagraph (a)(5)(i)
-URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292

+ Details

Name:	us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding
Namespace Prefix:	us-gaap
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

- Definition

This element represents the gross potential recoveries against the gross claim liability for financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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
-Number 163
-Paragraph 31
-Subparagraph a(5)
-Name Statement of Financial Accounting Standard (FAS)
-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 944
-SubTopic 40
-Section 55
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6933462&loc=SL5751133-161288

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 9
-Subparagraph (a)(5)(v)
-URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292

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- Definition

This element represents the net discount consisting of the difference between the discount related to the claim liability for and potential recoveries thereof related to financial guarantee insurance contracts presented in the context of each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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 163
-Paragraph 31
-Subparagraph a(6)
-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 944
-SubTopic 40
-Section 55
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6933462&loc=SL5751133-161288

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 9
-Subparagraph (a)(5)(vi)
-URI http://asc.fasb.org/extlink&oid=6933314&loc=SL5749324-161292

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- Definition

This element represents the remaining weighted average contract period of financial guarantee insurance contracts for each surveillance grouping or category used by management to monitor and track potential deterioration in the credit worthiness of the insured party's ability to meet its financial obligations related to the contracts underlying financial guarantee insurance contracts the entity has issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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 163
-Paragraph 31
-Subparagraph a(2)
-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 944
-SubTopic 40
-Section 55
-Paragraph 32
-URI http://asc.fasb.org/extlink&oid=6933462&loc=SL5751133-161288

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-SubTopic 40
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-Subparagraph (a)(5)(ii)
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 163
-Section Appendix A
-Paragraph A13
-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 163
-Paragraph 31
-Subparagraph a(9)
-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 944
-SubTopic 40
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Financial Guaranty Contracts Accounted for as Insurance (Details 12) (USD $) In Millions, unless otherwise specified	6 Months Ended	12 Months Ended
	Jun. 30, 2011 Y Contracts	Dec. 31, 2010 Y Contracts	Jun. 30, 2010	Dec. 31, 2009
Reserves (salvage)
Total BIG, Net	$ 92.1	$ (405.0)
Effect of consolidating FG VIEs	(128.1)	(42.7)
Total	220.2	(362.3)
BIG 1 \| Financial Guaranty
Number of risks
Gross	151	120
Ceded	(60)	(46)
Remaining weighted average contract period
Gross (in years)	11.5	11.7
Ceded (in years)	14.8	15.9
Principal
Gross	7,724.4	6,246.5
Ceded	(847.40)	(726.00)
Interest
Gross	4,074.5	3,622.7
Ceded	(655.8)	(581.3)
Total net outstanding exposure
Gross	11,798.9	9,869.2
Ceded	(1,503.2)	(1,307.3)
Expected cash flows
Gross	228.5	303.9
Ceded	(8.4)	(20.2)
Less: Potential recoveries
Gross	378.2	375.2
Ceded	(26.9)	(37.4)
Discount
Gross	(42.3)	21.0
Ceded	1.1	5.5
Present value of expected cash flows
Gross	(107.4)	(92.3)
Ceded	17.4	11.7
Deferred premium revenue
Gross	141.8	169.9
Ceded	(14.4)	(16.9)
Reserves (salvage)
Gross	(115.9)	(112.9)
Ceded	17.9	12.4
BIG 2 \| Financial Guaranty
Number of risks
Gross	84	97
Ceded	(29)	(41)
Remaining weighted average contract period
Gross (in years)	9.3	8.5
Ceded (in years)	7.1	8.0
Principal
Gross	5,245.6	5,825.8
Ceded	(207.50)	(180.10)
Interest
Gross	2,566.7	2,578.5
Ceded	(70.4)	(70.1)
Total net outstanding exposure
Gross	7,812.3	8,404.3
Ceded	(277.9)	(250.2)
Expected cash flows
Gross	1,548.4	2,019.8
Ceded	(85.8)	(68.9)
Less: Potential recoveries
Gross	633.7	533.0
Ceded	(23.4)	(16.6)
Discount
Gross	441.9	610.4
Ceded	(38.3)	(21.5)
Present value of expected cash flows
Gross	472.8	876.4
Ceded	(24.1)	(30.8)
Deferred premium revenue
Gross	357.7	569.8
Ceded	(23.4)	(30.3)
Reserves (salvage)
Gross	281.4	413.0
Ceded	(14.6)	(9.5)
BIG 3 \| Financial Guaranty
Number of risks
Gross	129	115
Ceded	(51)	(42)
Remaining weighted average contract period
Gross (in years)	8.7	8.8
Ceded (in years)	6.0	6.0
Principal
Gross	8,102.6	7,954.5
Ceded	(678.40)	(673.60)
Interest
Gross	2,343.8	2,490.7
Ceded	(178.3)	(186.3)
Total net outstanding exposure
Gross	10,446.4	10,445.2
Ceded	(856.7)	(859.9)
Expected cash flows
Gross	2,715.3	2,256.6
Ceded	(144.3)	(133.2)
Less: Potential recoveries
Gross	2,229.6	2,543.6
Ceded	(103.8)	(197.5)
Discount
Gross	83.1	139.6
Ceded	7.8	7.9
Present value of expected cash flows
Gross	402.6	(426.6)
Ceded	(48.3)	56.4
Deferred premium revenue
Gross	1,084.6	995.9
Ceded	(129.9)	(120.7)
Reserves (salvage)
Gross	(86.3)	815.9
Ceded	(7.5)	105.8
Financial Guaranty
Number of risks
Total BIG, Net	364	332
Total	364	332
Remaining weighted average contract period
Total BIG, Net (in years)	9.8	9.6
Total (in years)	9.8	9.6
Principal
Total BIG, Net	19,339.3	18,447.1
Total	19,339.3	18,447.1
Interest
Total BIG, Net	8,080.5	7,854.2
Total	8,080.5	7,854.2
Total net outstanding exposure
Total BIG, Net	27,419.8	26,301.3
Total	27,419.8	26,301.3
Expected cash flows
Total BIG, Net	4,253.7	4,358.0
Effect of Consolidating VIEs	(593.8)	(384.2)
Total	3,659.9	3,973.8
Less: Potential recoveries
Total BIG, Net	3,087.4	3,200.3
Effect of Consolidating VIEs	(588.2)	(354.8)
Total	2,499.2	2,845.5
Discount
Total BIG, Net	453.3	762.9
Effect of Consolidating VIEs	(11.2)	19.8
Total	442.1	782.7
Present value of expected cash flows
Total BIG, Net	713.0	394.8	753.3	1,027.0
Effect of Consolidating VIEs	5.6	(49.2)
Total	718.6	345.6
Deferred premium revenue
Total BIG, Net	1,416.4	1,567.7
Effect of Consolidating VIEs	(420.9)	(263.9)
Total	995.5	1,303.8
Reserves (salvage)
Total BIG, Net	90.0	(407.1)
Total	$ 218.1	$ (364.4)