XML 55 R42.htm IDEA: XBRL DOCUMENT
v3.25.3

Outstanding Exposure - BIG Net Par Outstanding (Details) $ in Millions | Sep. 30, 2025 USD ($) risk | Dec. 31, 2024 USD ($) risk
--- | --- | ---
Schedule of Insured Financial Obligations [Line Items] |  |
Net par outstanding, credit derivative | $ 3,759 | $ 4,212
Net | 274,875 | 261,552
BIG |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net par outstanding, financial guaranty insurance | 11,349 | 10,150
Net par outstanding, credit derivative | 29 | 32
Net | $ 11,378 | $ 10,182
Number of risks, financial guaranty insurance | risk | 197 | 207
Number of risks, credit derivative | risk | 7 | 7
Number of risks | risk | 204 | 214
BIG | BIG 1 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net par outstanding, financial guaranty insurance | $ 7,226 | $ 8,074
Net par outstanding, credit derivative | 25 | 28
Net | $ 7,251 | $ 8,102
Number of risks, financial guaranty insurance | risk | 92 | 98
Number of risks, credit derivative | risk | 3 | 3
Number of risks | risk | 95 | 101
BIG | BIG 2 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net par outstanding, financial guaranty insurance | $ 2,893 | $ 702
Net par outstanding, credit derivative | 4 | 4
Net | $ 2,897 | $ 706
Number of risks, financial guaranty insurance | risk | 10 | 12
Number of risks, credit derivative | risk | 1 | 1
Number of risks | risk | 11 | 13
BIG | BIG 3 |  |
Schedule of Insured Financial Obligations [Line Items] |  |
Net par outstanding, financial guaranty insurance | $ 1,230 | $ 1,374
Net par outstanding, credit derivative | 0 | 0
Net | $ 1,230 | $ 1,374
Number of risks, financial guaranty insurance | risk | 95 | 97
Number of risks, credit derivative | risk | 3 | 3
Number of risks | risk | 98 | 100

X
- Definition Represents the number of unique credits in the insured portfolio accounted for as credit derivative. + References No definition available. + Details
Name: | ago_FinancialGuarantyContractsAccountedForAsCreditDerivativesNumberOfContracts
Namespace Prefix: | ago_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

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 Represents the number of unique credits in the insured portfolio. + References No definition available. + Details
Name: | ago_InsuredFinancialObligationsNumberofContracts
Namespace Prefix: | ago_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the outstanding principal amounts of the underlying insured obligations for financial guaranty contracts, after netting out ceded contracts. + References No definition available. + Details
Name: | ago_InsuredFinancialObligationsOutstandingPrincipalAmountNet
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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, before adjusting for the effect of consolidating VIEs. + References No definition available. + Details
Name: | ago_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationInsuredContractualPaymentsOutstandingPrincipalNet
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition [Line Items] for Schedule of Insured Financial Obligations [Table] + References No definition available. + Details
Name: | ago_ScheduleofInsuredFinancialObligationsLineItems
Namespace Prefix: | ago_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- 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/exampleRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 55 -Paragraph 34 -Publisher FASB -URI https://asc.fasb.org/1943274/2147480046/944-40-55-34 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 40 -Name Accounting Standards Codification -Section 50 -Paragraph 9 -Subparagraph (a)(5)(i) -Publisher FASB -URI https://asc.fasb.org/1943274/2147480081/944-40-50-9 + Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationNumberOfContractsIssuedAndOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_InternalCreditAssessmentAxis=us-gaap_InternalNoninvestmentGradeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ago_InternalNoninvestmentGradeLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ago_InternalNoninvestmentGradeLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_ScheduleOfInsuredFinancialObligationsWithCreditDeteriorationBySurveillanceCategoryAxis=ago_InternalNoninvestmentGradeLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |