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Expected Loss to be Paid (Recovered) - Additional Information (Details) $ in Millions | 3 Months Ended | 6 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | --- | ---
Jun. 30, 2022 USD ($) | Jun. 30, 2021 USD ($) | Jun. 30, 2022 USD ($) scenario Payment Curve | Jun. 30, 2021 USD ($) | Dec. 31, 2021 USD ($) scenario | Mar. 31, 2022 USD ($) | Mar. 31, 2021 USD ($) | Dec. 31, 2020 USD ($)
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Period of insured credit performance of guaranteed obligations (in some cases over) |  |  | 30 years |  |  |  |  |
Discount factor (as a percent) |  |  | 2.90% |  | 1.02% |  |  |
Net Expected Loss to be Paid (Recovered) | $ 442 | $ 466 | $ 442 | $ 466 | $ 411 | $ 432 | $ 472 | $ 529
Loss and LAE Reserve paid | 7 | 6 | 20 | 10 |  |  |  |
Expected LAE to be paid | 14 |  | 14 |  | 26 |  |  |
Ceded expected loss to be recovered (paid) | (3) |  | (3) |  | 10 |  |  |
Net par outstanding | 232,812 |  | 232,812 |  | 236,392 |  |  |
Net economic loss development (benefit) | $ (32) | (20) | $ (76) | (7) |  |  |  |
Additional loss recovery assumption, recovery period |  |  | 5 years |  |  |  |  |
Loss recovery assumption, additional increase in recovery projection, percent | 40.00% |  | 40.00% |  |  |  |  |
Loss recovery assumption, additional increase in recovery projection, economic benefit | $ 40 |  | $ 40 |  |  |  |  |
Loss recovery assumption, additional decrease in recovery projection, percent | 20.00% |  | 20.00% |  |  |  |  |
Loss recovery assumption, additional decrease in recovery projection, economic loss | $ 40 |  | $ 40 |  |  |  |  |
Public Finance Stockton Pension Obligation Bonds |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 100 |  | 100 |  |  |  |  |
Public finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 217 | 243 | 217 | 243 | 209 | 191 | 252 | 341
Net par outstanding | 224,095 |  | 224,095 |  | 227,164 |  |  |
Net economic loss development (benefit) | 6 | 0 | (44) | 3 |  |  |  |
Other structured finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 46 | 45 | 46 | 45 | 52 | 46 | 39 | 40
Net par outstanding | 6,546 |  | 6,546 |  | 6,837 |  |  |
Net economic loss development (benefit) | 1 | 8 | 0 | 7 |  |  |  |
BIG |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 5,386 |  | 5,386 |  | 7,356 |  |  |
BIG | Public finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 4,091 |  | 4,091 |  | 5,972 |  |  |
BIG | Other structured finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 110 |  | 110 |  | $ 119 |  |  |
BIG | Student Loan |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 51 |  | 51 |  |  |  |  |
BIG | Life insurance transactions |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 40 |  | $ 40 |  |  |  |  |
United States |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net expected loss to be paid after recoveries for representations and warranties, percent |  |  | 98.60% |  | 97.20% |  |  |
United States | Public finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 210 | 221 | $ 210 | 221 | $ 197 | 181 | 228 | 305
Net par outstanding | 179,648 |  | 179,648 |  | 177,219 |  |  |
Net economic loss development (benefit) | 8 | 1 | (40) | 16 |  |  |  |
United States | RMBS |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 179 | 178 | 179 | 178 | 150 | $ 195 | $ 181 | $ 148
Net par outstanding | 2,171 |  | 2,171 |  | 2,391 |  |  |
Net economic loss development (benefit) | $ (39) | (28) | $ (32) | (17) |  |  |  |
United States | RMBS | Second Lien |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Period from plateau to intermediate conditional default rate (in months) |  |  | 28 months |  |  |  |  |
United States | RMBS | Home Equity Line of Credit |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Final CPR | 1.00% |  | 1.00% |  |  |  |  |
United States | RMBS | First Lien |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | $ 195 |  | $ 195 |  | $ 167 |  |  |
Net economic loss development (benefit) | $ (14) | (14) | $ 4 | 11 |  |  |  |
Number of delinquent payments | Payment |  |  | 2 |  |  |  |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  | 36 months |  |  |  |  |
Projected loss assumptions, final CPR, period for voluntary prepayments to continue |  |  | 12 months |  |  |  |  |
Percent of deferred loan balances to be recovered |  |  | 20.00% |  |  |  |  |
Intermediate conditional default rate (as a percent) | 5.00% |  | 5.00% |  |  |  |  |
Number of scenarios weighted in estimating expected losses | scenario |  |  | 5 |  | 5 |  |  |
United States | 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 from plateau to intermediate conditional default rate (in months) |  |  | 12 months |  |  |  |  |
Intermediate conditional default rate as a percentage of plateau conditional default rate |  |  | 20.00% |  |  |  |  |
Final conditional default rate as a percentage of plateau conditional default rate |  |  | 5.00% |  |  |  |  |
Projected loss assumptions, final CPR, period for voluntary prepayments to continue |  |  | 1 year |  |  |  |  |
Default from delinquentor rate, term |  |  | 36 months |  |  |  |  |
Performing or projected to reperform, projection period |  |  | 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% |  | 40.00% |  |  |  |  |
Projected loss assumptions, period to reach final loss severity rate |  |  | 2 years 6 months |  |  |  |  |
Final CPR | 15.00% |  | 15.00% |  |  |  |  |
United States | RMBS | First Lien | More Stressful Environment |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Period from plateau to intermediate conditional default rate (in months) |  |  | 15 months |  |  |  |  |
Projected loss assumptions, increase (decrease) in expected loss to be paid, net |  |  | $ (15) |  |  |  |  |
United States | 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 from plateau to intermediate conditional default rate (in months) |  |  | 9 months |  |  |  |  |
Projected loss assumptions, increase (decrease) in expected loss to be paid, net |  |  | $ 11 |  |  |  |  |
Decrease in the plateau period used to calculate potential change in loss estimate (in months) |  |  | 6 months |  |  |  |  |
United States | RMBS | First Lien | Most Stressful |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Projected loss assumptions, period to reach final loss severity rate |  |  | 9 years |  |  |  |  |
United States | RMBS | Second Lien |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | $ (16) |  | $ (16) |  | $ (17) |  |  |
Net economic loss development (benefit) | $ (25) | $ (14) | $ (36) | $ (28) |  |  |  |
Period from plateau to intermediate conditional default rate (in months) |  |  | 28 months |  |  |  |  |
Period of loan default estimate |  |  | 6 months |  |  |  |  |
Number of preceding months average liquidation rates used to estimate loan default rate |  |  | 6 months |  |  |  |  |
Projected loss assumptions, period of consistent conditional default rate |  |  | 6 months |  |  |  |  |
Stress period (in months) |  |  | 34 months |  |  |  |  |
Monthly delinquency threshold |  |  | 6 months |  |  |  |  |
Loss recovery assumption (as a percent) | 2.00% |  | 2.00% |  | 2.00% |  |  |
Number of conditional default rate curves modeled in estimating losses | Curve |  |  | 5 |  |  |  |  |
Liquidation rate | 30.00% |  | 30.00% |  |  |  |  |
United States | RMBS | Second Lien | Home Equity Line of Credit and Closed-end Mortgage |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Final CPR | 15.00% |  | 15.00% |  |  |  |  |
United States | RMBS | Second Lien | Base Scenario |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Stress period (in months) |  |  | 34 months |  |  |  |  |
United States | RMBS | Second Lien | Most Stressful |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  | 8 months |  |  |  |  |
Period from plateau to intermediate conditional default rate (in months) |  |  | 31 months |  |  |  |  |
Stress period (in months) |  |  | 39 months |  |  |  |  |
Increase in conditional default rate ramp down period |  |  | 3 months |  |  |  |  |
United States | RMBS | Second Lien | Most Stressful | Home Equity Line of Credit |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Change in estimate for increased conditional default rate plateau period |  |  | $ 5 |  |  |  |  |
United States | RMBS | Second Lien | Least Stressful |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Stress period (in months) |  |  | 29 months |  |  |  |  |
Period of constant conditional default rate (in months) |  |  | 4 months |  |  |  |  |
Decreased conditional default rate ramp down period |  |  | 25 months |  |  |  |  |
Change in estimate for decreased prepayment rate, Percent |  |  | 10.00% |  |  |  |  |
United States | RMBS | Second Lien | Least Stressful | 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 |  |  | $ 5 |  |  |  |  |
United States | 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 |  |  |  |  |
United States | BIG | Public finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | $ 3,570 |  | $ 3,570 |  | $ 5,372 |  |  |
United States | BIG | RMBS |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 1,185 |  | 1,185 |  | 1,265 |  |  |
Puerto Rico |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 2,227 |  | 2,227 |  | 3,572 |  |  |
Puerto Rico | BIG |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net par outstanding | 2,227 |  | 2,227 |  | 3,572 |  |  |
Non United States | Public finance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 7 |  | 7 |  | $ 12 |  |  |
Net economic loss development (benefit) | $ (2) |  | $ (4) |  |  |  |  |
Minimum |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Risk free discount rate |  |  | 1.67% |  | 0.00% |  |  |
Maximum |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Risk free discount rate |  |  | 3.41% |  | 1.98% |  |  |

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- 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
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- 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
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- Definition Represents the initial 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
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- Definition Guarantor Obligations, Net Expected Loss to be Paid After Recoveries for Representations and Warranties + References No definition available. + Details
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- Definition Guarantor Obligations, Net Expected Loss to be Paid After Recoveries for Representations and Warranties, Percent + References No definition available. + Details
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- Definition Guarantor Obligations, Projected Loss Assumption, Deferred Loan Balances to be Recovered, Percent + References No definition available. + Details
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- Definition Guarantor Obligations, Projected Loss Assumption, Final Conditional Prepayment Rates, Final Rate, Term + References No definition available. + Details
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- Definition Guarantor Obligations, Projected Loss Assumptions, Conditional Default Rate, Plateau Rate, Performing or Projected to Reperform, Projection Period + References No definition available. + Details
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- 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
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- 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
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- 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
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- 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
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- Definition Represents the intermediate conditional default rate on a pool of insured obligations as a percentage of the plateau conditional default rate. + References No definition available. + Details
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- Definition Guarantor Obligations, Projected Loss Assumptions, Liquidation Rate + References No definition available. + Details
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- 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
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- Definition Guarantor Obligations, Projected Loss Assumptions, Loss Severity, Subsequent Period + References No definition available. + Details
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- 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
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- 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
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- 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
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- Definition Initial Period for Which Borrower Can Pay Only Interest Payments + References No definition available. + Details
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- Definition Insured Financial Obligations, Liability for Unpaid Claims Adjustment Expense, Claims Paid + References No definition available. + Details
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- 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
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- Definition Insured Financial Obligations, Projected Loss Assumptions, Conditional Prepayment Rate, Final Rate + References No definition available. + Details
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- Definition Loss Estimate Sensitivity Analysis, Change In Estimate For Decreased Prepayment Rate, Percent + References No definition available. + Details
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- 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
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- 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
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- 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
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- Definition Loss Recovery Assumption, Additional Decrease in Recovery Projection, Economic Loss + References No definition available. + Details
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- Definition Loss Recovery Assumption, Additional Decrease in Recovery Projection, Percent + References No definition available. + Details
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- Definition Loss Recovery Assumption, Additional Increase in Recovery Projection, Economic Benefit + References No definition available. + Details
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- Definition Loss Recovery Assumption, Additional Increase in Recovery Projection, Percent + References No definition available. + Details
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- Definition Monthly Delinquency Threshold, Period + References No definition available. + Details
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- Definition Number of Preceding Months Liquidation Rates Used to Estimate Loan Default Rate + References No definition available. + Details
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- Definition Number of Delinquent Payments + References No definition available. + Details
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- Definition Represents the period for which the entity estimates the number of insured obligations that will default. + References No definition available. + Details
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- 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
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- Definition [Line Items] for Schedule of Expected Losses to be Paid [Table] + References No definition available. + Details
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- Definition Represents the total stress period. + References No definition available. + Details
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