XML 102 R75.htm IDEA: XBRL DOCUMENT
v3.25.0.1

Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) U.S. RMBS (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Schedule of Expected Losses to be Paid [Line Items] |  |  |
Net Economic Loss Development (Benefit) | $ (3) | $ 164 | $ (125)
U.S. | RMBS |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |
Net Economic Loss Development (Benefit) | (75) | (56) | (143)
First Lien | U.S. | RMBS |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |
Net Economic Loss Development (Benefit) | 27 | (7) | (36)
Second Lien | U.S. | RMBS |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |
Net Economic Loss Development (Benefit) | $ (48) | $ (49) | $ (107)

X
- Definition Guarantor Obligations, Net Expected Loss Development After Recoveries for Representations and Warranties + References No definition available. + Details
Name: | ago_GuarantorObligationsNetExpectedLossDevelopmentAfterRecoveriesforRepresentationsandWarranties
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition [Line Items] for Schedule of Expected Losses to be Paid [Table] + References No definition available. + Details
Name: | ago_ScheduleofExpectedLossestobePaidLineItems
Namespace Prefix: | ago_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | srt_StatementGeographicalAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_UnderlyingAssetClassAxis=us-gaap_ResidentialMortgageBackedSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionLoanCategoryAxis=us-gaap_FirstMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_MortgageLoansOnRealEstateDescriptionLoanCategoryAxis=us-gaap_SecondMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |