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
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Period Type:	instant

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

No definition available.

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Namespace Prefix:	ago_
Data Type:	xbrli:stringItemType
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Amount of premium receivable under financial guarantee insurance contract to be collected in fourth fiscal quarter following current year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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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Amount of premium receivable under financial guarantee insurance contract to be collected in third fiscal quarter following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Period Type:	instant

Amount of premium receivable under financial guarantee insurance contract to be collected in eleventh through fifteenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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 receivable under financial guarantee insurance contract to be collected in sixteenth through twentieth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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_
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Period Type:	instant

Amount of premium receivable under financial guarantee insurance contract to be collected in sixth through tenth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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_
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Amount of premium receivable under financial guarantee insurance contract to be collected in fifth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Data Type:	xbrli:monetaryItemType
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Period Type:	instant

Amount of premium receivable under financial guarantee insurance contract to be collected in second fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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

Amount of premium receivable under financial guarantee insurance contract to be collected in fourth fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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Namespace Prefix:	us-gaap_
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Amount of premium receivable under financial guarantee insurance contract to be collected in third fiscal year following current fiscal year. Excludes interim and annual periods when interim periods are reported from current statement of financial position date (rolling approach).

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

Amount of premium receivables under financial guarantee insurance contracts.

No definition available.