XML 85 R71.htm IDEA: XBRL DOCUMENT v3.23.3

Contracts Accounted for as Credit Derivatives - Credit Derivatives Subordination and Ratings (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2023	Dec. 31, 2022
Credit Derivatives
Estimated remaining weighted average life of credit derivatives (in years)	11 years 4 months 24 days	12 years 9 months 18 days
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	$ 3,489	$ 3,203
Net Fair Value Asset (Liability)	(49)	(162)
Expected loss to be recovered	3	3
Public finance | United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,074	1,175
Net Fair Value Asset (Liability)	(15)	(79)
Public finance | Non United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	1,478	1,565
Net Fair Value Asset (Liability)	(19)	(58)
Structured finance | United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	327	342
Net Fair Value Asset (Liability)	(13)	(22)
Structured finance | Non United States
Net Par Outstanding on Credit Derivatives
Net Par Outstanding	610	121
Net Fair Value Asset (Liability)	$ (2)	$ (3)

X

- Definition

Expected Loss on Credit Derivative to Be Paid (Recovered), Including Representation and Warranty Liability (Benefit)

+ References

No definition available.

+ Details

Name:	ago_ExpectedLossOnCreditDerivativeToBePaidRecoveredIncludingRepresentationAndWarrantyLiabilityBenefit
Namespace Prefix:	ago_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- References

No definition available.

+ Details

Name:	ago_FinancialGuarantyContractsAccountedForAsCreditDerivativesAbstract
Namespace Prefix:	ago_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Represents the outstanding principal amounts of the underlying insured obligations that are accounted for as credit derivatives, net of protection purchased.

+ References

No definition available.

+ Details

Name:	ago_FinancialGuarantyContractsAccountedforasCreditDerivativesOutstandingPrincipalAmount
Namespace Prefix:	ago_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Average period covered by credit risk derivative contracts, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4K
-Subparagraph (a)(1)
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4K

+ Details

Name:	us-gaap_AverageTermOfCreditRiskDerivatives1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

X

- Definition

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.

+ References

No definition available.

+ Details

Name:	us-gaap_CreditDerivativesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Fair value of credit risk derivative asset after deduction of credit risk derivative liability.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4K
-Subparagraph (c)
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4K

+ Details

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

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=ago_PublicFinanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	srt_StatementGeographicalAxis=ago_NonUnitedStatesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_UnderlyingAssetClassAxis=us-gaap_StructuredFinanceMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: