Name:	ago_FinancialGuaranteeInsuranceContractsPremiumReceivablePremiumExpectedtobeCollectedBeyondYear20
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Represents the cash collected against the premiums for financial guaranty insurance contracts of variable interest entity.

No definition available.

Name:	ago_FinancialGuaranteeInsuranceContractsPremiumsExpectedtobeCollected
Namespace Prefix:	ago_
Data Type:	xbrli:monetaryItemType
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Period Type:	instant

[Line Items] for Financial Guarantee Insurance Premiums [Table]

No definition available.

Name:	ago_FinancialGuaranteeInsurancePremiumsLineItems
Namespace Prefix:	ago_
Data Type:	xbrli:stringItemType
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Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the next fiscal quarter following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 50

-Paragraph 3

-Subparagraph (b)(1)

-URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290

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

Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the eleventh through the fifteenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 50

-Paragraph 3

-Subparagraph (b)(2)

-URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290

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

Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the sixteenth through the twentieth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 50

-Paragraph 3

-Subparagraph (b)(2)

-URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290

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

Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the sixth through the tenth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 310

-Section 50

-Paragraph 3

-Subparagraph (b)(2)

-URI http://asc.fasb.org/extlink&oid=6933075&loc=SL5748726-161290

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Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the fifth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the second fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_FinancialGuaranteeInsuranceContractsPremiumExpectedToBeCollectedMoreThanOneAndWithinTwoYearsFromBalanceSheetDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the fourth fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

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

Amount of premium receivables under financial guarantee insurance contracts expected to be collected in the third fiscal year following the latest fiscal year. Excludes interim and annual periods when interim periods are reported on a rolling approach, from latest balance sheet date.

Name:	us-gaap_FinancialGuaranteeInsuranceContractsPremiumExpectedToBeCollectedMoreThanTwoAndWithinThreeYearsFromBalanceSheetDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Amount of premium receivables under financial guarantee insurance contracts.

No definition available.