XML 97 R75.htm IDEA: XBRL DOCUMENT
v3.24.0.1

Expected Loss to be Paid (Recovered) - Narrative (Details) $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2023 | Mar. 31, 2023 | Jun. 30, 2023 | Dec. 31, 2023 USD ($) scenario Payment Curve | Dec. 31, 2022 USD ($) scenario | Dec. 31, 2021 USD ($)
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Period of insured credit performance of guaranteed obligations (in some cases over) |  |  |  | 30 years |  |
Loss and LAE reserve paid |  |  |  | $ 25 | $ 33 | $ 36
Expected LAE to be paid |  |  |  | $ 22 | $ 11 |
Projected loss assumptions, number of scenarios considered | scenario |  |  |  | 5 | 5 |
Recovery period |  |  |  | 5 years |  |
First Lien |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Effect of recovery |  |  |  | $ 7 |  |
Second Lien |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Effect of recovery |  |  |  | $ 31 |  |
U.S. | RMBS | First Lien |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Number of delinquent payments | Payment |  |  |  | 2 |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  |  | 36 months |  |
Final conditional prepayment rates, term |  |  |  |  | 12 months |
Deferred loan balances to be recovered, percent |  |  |  | 30.00% |  |
Intermediate conditional default rate (as a percent) |  |  |  | 5.00% |  |
U.S. | RMBS | First Lien | More Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Deferred loan balances to be recovered, percent |  | 10.00% |  |  |  |
U.S. | RMBS | First Lien | Least Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Deferred loan balances to be recovered, percent |  | 50.00% |  |  |  |
U.S. | RMBS | First Lien | Base Scenario |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Deferred loan balances to be recovered, percent | 30.00% | 20.00% | 20.00% |  |  |
U.S. | RMBS | First Lien | Base Scenario |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  |  | 36 months |  |
Period to reach intermediate conditional default rate |  |  |  | 12 months |  |
Final conditional default rate as a percentage of plateau conditional default rate |  |  |  | 5.00% |  |
Projected loss assumptions, Final CDR, Period for voluntary prepayments to continue |  |  |  | 1 year |  |
Period for which estimated defaults are attributed to loans currently delinquent or in foreclosure |  |  |  | 36 months |  |
Projected loss assumptions, loss severity, subsequent period |  |  |  | 18 months |  |
Estimated loss severity rate, one through six months (as a percent) |  |  |  | 18 months |  |
Loss severity (as a percent) |  |  |  | 40.00% |  |
Projected loss assumptions, period to reach final loss severity rate |  |  |  | 2 years 6 months |  |
U.S. | RMBS | First Lien | More Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Period to reach intermediate conditional default rate |  |  |  | 16 months |  |
Projected loss assumptions, period to reach final loss severity rate |  |  |  | 9 years |  |
Deferred loan balances to be recovered, percent |  |  |  | 10.00% |  |
Projected loss assumptions, increase (decrease) in expected loss to be paid, net |  |  |  | $ 30 |  |
U.S. | RMBS | First Lien | Least Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  |  | 30 months |  |
Period to reach intermediate conditional default rate |  |  |  | 8 months |  |
Deferred loan balances to be recovered, percent |  |  |  | 50.00% |  |
Projected loss assumptions, increase (decrease) in expected loss to be paid, net |  |  |  | $ 22 |  |
Decrease in the plateau period used to calculate potential change in loss estimate (in months) |  |  |  | 6 months |  |
U.S. | RMBS | Second Lien |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Period of conditional default rate downward trend |  |  |  | 1 year |  |
Percent of original period of consistent conditional default rate |  |  |  | 5.00% |  |
Loss recovery assumption |  |  |  | 2.00% | 2.00% |
Liquidation rate | 30.00% |  |  | 40.00% |  |
Conditional prepayment rate, final rate |  |  |  | 15.00% |  |
Number of conditional default rate curves modeled in estimating losses | Curve |  |  |  | 5 |  |
U.S. | RMBS | Second Lien | More Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Deferred loan balances to be recovered, percent |  |  |  | 10.00% |  |
U.S. | RMBS | Second Lien | Least Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Deferred loan balances to be recovered, percent |  |  |  | 80.00% |  |
U.S. | RMBS | Second Lien | Base Scenario |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Current conditional prepayment rate used in alternate scenario for loss estimate (as a percent) |  |  |  |  | 15.00% |
U.S. | RMBS | Second Lien | More Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  |  | 42 months |  |
Period to reach intermediate conditional default rate |  |  |  | 16 months |  |
Increase in conditional default rate ramp down period |  |  |  | 4 months |  |
Stress period (in months) |  |  |  | 58 months |  |
U.S. | RMBS | Second Lien | More Stressful Environment | Home Equity Line of Credit |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Change in estimate for increased conditional default rate plateau period |  |  |  | $ 87 |  |
U.S. | RMBS | Second Lien | Least Stressful Environment |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Stress period (in months) |  |  |  | 38 months |  |
Period of constant conditional default rate (in months) |  |  |  | 30 months |  |
Decreased conditional default rate ramp down period |  |  |  | 8 months |  |
Ultimate prepayment rate |  |  |  | 10.00% |  |
U.S. | RMBS | Second Lien | Least Stressful Environment | Home Equity Line of Credit |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Change in estimate for decreased conditional default rate ramp down period |  |  |  | $ 118 |  |
U.S. | Home Equity Line of Credit |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Initial period for which borrower can pay only interest payments |  |  |  | 10 years |  |
U.S. | Home Equity Line of Credit Insured |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Initial period for which borrower can pay only interest payments |  |  |  | 15 years |  |

X
- Definition Additional Loss Recovery Assumption, Recovery Period + References No definition available. + Details
Name: | ago_AdditionalLossRecoveryAssumptionRecoveryPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of possible conditional default rate curves modeled and probability weighted in estimating loss on insured obligations. + References No definition available. + Details
Name: | ago_ConditionalDefaultRateNumberOfCurves
Namespace Prefix: | ago_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition The period for which the conditional default rate of a pool of insured obligations is held constant, following the period for which default is estimated based on past due balances. + References No definition available. + Details
Name: | ago_ConditionalDefaultRatePlateauPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expected Loss Adjustment Expense To Be Paid + References No definition available. + Details
Name: | ago_ExpectedLossAdjustmentExpenseToBePaid
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Represents the period over which defaults projected to occur on a pool of insured obligations represent defaults that can be attributed to obligations that are currently delinquent or in foreclosure. + References No definition available. + Details
Name: | ago_GuarantorObligationsDefaultfromDelinquentorRatePeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumption, Deferred Loan Balances to be Recovered, Percent + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionDeferredLoanBalancesToBeRecoveredPercent
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumption, Effect of Recovery + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionEffectOfRecovery
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumption, Final Condition Default Rates, Final Rate, Term + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionFinalConditionDefaultRatesFinalRateTerm
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumption, Final Conditional Prepayment Rates, Final Rate, Term + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionFinalConditionalPrepaymentRatesFinalRateTerm
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumptions, Conditional Default Rate, Intermediate Rate + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsConditionalDefaultRateIntermediateRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the period over which the application of the constant conditional default rate would produce approximately the amount of defaults calculated for each delinquency category of insured financial obligations. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsConditionalDefaultRatePlateauRateProjectionPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the decrease in the conditional default rate plateau period for which the change in loss estimate for a pool of insured obligations is calculated. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsConditionalDefaultRatePlateauRateProjectionPeriodDecrease
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the current conditional prepayment rate used in an alternate scenario for which the change in loss estimate for a pool of insured obligations is calculated. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsConditionalPrepaymentRateFinalRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the final conditional default rate on a pool of insured obligations as a percentage of the plateau conditional default rate. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsFinalConditionalDefaultRateasPercentageofPlateauConditionalDefaultRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the change in expected loss on a pool of insured obligations that would result from an increase in the conditional default rate plateau period and loss severity recovery period. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsIncreaseDecreaseinExpectedLosstobePaidNet
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumptions, Liquidation Rate + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsLiquidationRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Guarantor Obligations, Projected Loss Assumptions, Loss Severity, Initial Period + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsLossSeverityInitialPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the present value of the final level of assumed lifetime losses on a pool of insured obligations as a percentage of principal balance. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsLossSeverityRateFinalRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Guarantor Obligations, Projected Loss Assumptions, Loss Severity, Subsequent Period + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsLossSeveritySubsequentPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of scenarios used during the current period in estimation of expected loss on a pool of insured obligations. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsNumberofScenariosConsidered
Namespace Prefix: | ago_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumptions, Percent of Original Period Of Consistent Conditional Default Rate + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsPercentOfOriginalPeriodOfConsistentConditionalDefaultRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Guarantor Obligations, Projected Loss Assumptions, Period Of Conditional Default Rate Downward Trend + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsPeriodOfConditionalDefaultRateDownwardTrend
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the period over which the conditional prepayment rate assumed for a pool of insured obligations trends from the initial to the final rate. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsPeriodtoReachFinalLossSeverityRate
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the period over which the conditional default rate on a pool of insured obligations is assumed to improve from the current level to an intermediate conditional default rate. + References No definition available. + Details
Name: | ago_GuarantorObligationsProjectedLossAssumptionsPeriodtoReachIntermediateConditionalDefaultRate
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Initial Period for Which Borrower Can Pay Only Interest Payments + References No definition available. + Details
Name: | ago_InitialPeriodforWhichBorrowerCanPayOnlyInterestPayments
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Insured Financial Obligations, Insured Credit Performance of Guaranteed Obligations, Term + References No definition available. + Details
Name: | ago_InsuredFinancialObligationsInsuredCreditPerformanceofGuaranteedObligationsTerm
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Insured Financial Obligations, Liability for Unpaid Claims Adjustment Expense, Claims Paid + References No definition available. + Details
Name: | ago_InsuredFinancialObligationsLiabilityforUnpaidClaimsAdjustmentExpenseClaimsPaid
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Insured Financial Obligations, Projected Loss Assumptions, Conditional Prepayment Rate, Final Rate + References No definition available. + Details
Name: | ago_InsuredFinancialObligationsProjectedLossAssumptionsConditionalPrepaymentRateFinalRate
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the change in expected loss on a pool of insured obligations that would result from a decrease in the conditional default rate ramp period. + References No definition available. + Details
Name: | ago_LossEstimateSensitivityAnalysisChangeInEstimateForDecreasedConditionalDefaultRateRampDownPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Loss Estimate Sensitivity Analysis, Change In Estimate For Decreased Prepayment Rate, Percent + References No definition available. + Details
Name: | ago_LossEstimateSensitivityAnalysisChangeInEstimateForDecreasedPrepaymentRatePercent
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the change in expected loss on a pool of insured obligations that would result from an increase in the conditional default rate plateau period. + References No definition available. + Details
Name: | ago_LossEstimateSensitivityAnalysisChangeInEstimateForIncreasedConditionalDefaultRatePlateauPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Represents the decreased conditional default rate ramp down period for which the change in loss estimate for a pool of insured obligations is calculated. + References No definition available. + Details
Name: | ago_LossEstimateSensitivityAnalysisDecreasedConditionalDefaultRateRampDownPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Loss Estimate Sensitivity Analysis Increase in Conditional Default Rate Ramp Down Period + References No definition available. + Details
Name: | ago_LossEstimateSensitivityAnalysisIncreaseInConditionalDefaultRateRampDownPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the percentage of assumed lifetime losses on a pool of insured obligations that is anticipated to be recovered. + References No definition available. + Details
Name: | ago_LossRecoveryAssumption
Namespace Prefix: | ago_
Data Type: | dtr-types1:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Delinquent Payments + References No definition available. + Details
Name: | ago_NumberofDelinquentPayments
Namespace Prefix: | ago_
Data Type: | xbrli:integerItemType
Balance Type: | na
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
- Definition Represents the total stress period. + References No definition available. + Details
Name: | ago_TotalStressPeriod
Namespace Prefix: | ago_
Data Type: | xbrli:durationItemType
Balance Type: | na
Period Type: | duration

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: |

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: | ago_DeferredLoanRecoveryScenarioAxis=ago_MoreStressfulEnvironmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ago_DeferredLoanRecoveryScenarioAxis=ago_LeastStressfulEnvironmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ago_DeferredLoanRecoveryScenarioAxis=ago_BaseScenarioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=ago_BaseScenarioMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=ago_MoreStressfulEnvironmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_StatementScenarioAxis=ago_LeastStressfulEnvironmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancialInstrumentAxis=us-gaap_HomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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