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Expected Loss to be Paid (Recovered) - Narrative (Details) $ in Millions |  | 3 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2022 | Sep. 30, 2022 | Dec. 31, 2022 USD ($) Payment Curve scenario | Dec. 31, 2021 USD ($) scenario | Dec. 31, 2020 USD ($) | Dec. 31, 2019 USD ($)
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Period of insured credit performance of guaranteed obligations (in some cases over) |  |  | 30 years |  |  |
Net Par Outstanding |  |  | $ 233,258 | $ 236,392 |  |
Net Expected Loss to be Paid (Recovered) |  |  | 522 | 411 | $ 529 | $ 737
Economic benefit for public finance transactions |  |  | $ 125 | $ 287 | (145) |
Projected loss assumptions, number of scenarios considered | scenario |  |  | 5 | 5 |  |
Recovery period |  |  | 5 years |  |  |
Additional increase in recovery projection, percent |  |  | 40.00% |  |  |
Additional increase in recovery projection, economic benefit |  |  | $ 37 |  |  |
Additional decrease in recovery projection, percent |  |  | 20.00% |  |  |
Additional decrease in recovery projection, economic loss |  |  | $ 37 |  |  |
Public finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 224,099 | $ 227,164 |  |
Net Expected Loss to be Paid (Recovered) |  |  | 412 | 209 | 341 | 554
Economic benefit for public finance transactions |  |  | (17) | 204 | (203) |
Other structured finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 7,203 | 6,837 |  |
Net Expected Loss to be Paid (Recovered) |  |  | 44 | 52 | 40 | 37
Economic benefit for public finance transactions |  |  | (1) | (17) | (13) |
BIG |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 5,892 | 7,356 |  |
BIG | Public finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 4,777 | 5,972 |  |
BIG | Other structured finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 105 | 119 |  |
BIG | Student Loan |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 47 |  |  |
BIG | Life insurance transactions |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 40 |  |  |
U.S. |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 187,864 |  |  |
U.S. | Public finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 179,636 | 177,219 |  |
Net Expected Loss to be Paid (Recovered) |  |  | 403 | 197 | 305 | 531
Economic benefit for public finance transactions |  |  | (19) | 182 | (190) |
U.S. | RMBS |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 1,956 | 2,391 |  |
Net Expected Loss to be Paid (Recovered) |  |  | 66 | 150 | 148 | 146
Economic benefit for public finance transactions |  |  | $ 143 | 100 | 71 |
Maximum number of payments behind to be considered performing borrower | Payment |  |  | 2 |  |  |
Period of maximum missed payments to be classified as performing borrower |  |  | 2 years |  |  |
U.S. | RMBS | Second Lien |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Period to reach intermediate conditional default rate |  |  | 12 months |  |  |
U.S. | RMBS | First Lien |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Economic benefit for public finance transactions |  |  | $ (36) | 0 | 45 |
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 |  |  | 20.00% |  |  |
Intermediate conditional default rate (as a percent) |  |  | 5.00% |  |  |
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 |  |  |
Projected loss assumptions, increase (decrease) in expected loss to be paid, net |  |  | $ 13 |  |  |
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 |  |  |
Projected loss assumptions, increase (decrease) in expected loss to be paid, net |  |  | $ 8 |  |  |
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] |  |  |  |  |  |
Economic benefit for public finance transactions |  |  | $ 107 | $ 100 | 26 |
Liquidation rate |  |  | 30.00% |  |  |
Period to reach intermediate conditional default rate | 28 months |  |  |  |  |
Period of consistent CDR | 6 months | 36 months |  |  |  |
Stress period (in months) | 34 months | 48 months |  |  |  |
Period of delinquency (in days) |  |  | 180 days |  |  |
Percentage of consistent conditional default rate |  | 5.00% |  |  |  |
Conditional prepayment rate, final rate |  |  | 15.00% |  |  |
Loss recovery assumption |  |  | 2.00% | 2.00% |  |
Number of conditional default rate curves modeled in estimating losses | Curve |  |  | 5 |  |  |
U.S. | RMBS | Second Lien | Base Scenario |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Period to reach intermediate conditional default rate |  |  | 28 months |  |  |
Current conditional prepayment rate used in alternate scenario for loss estimate (as a percent) |  |  | 15.00% |  |  |
Stress period (in months) |  |  | 34 months |  |  |
Period of constant conditional default rate (in months) |  |  | 6 months |  |  |
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 |  |  |
Stress period (in months) |  |  | 58 months |  |  |
Increase in conditional default rate ramp down period |  |  | 4 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 |  |  | $ 1 |  |  |
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 |  |  | $ 2 |  |  |
U.S. | RMBS | Second Lien | Base Scenario One |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Projected loss assumptions, CDR, plateau rate, projection period |  |  | 36 months |  |  |
Stress period (in months) |  |  | 48 months |  |  |
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 |  |  |
Modified loans reset to fully amortize, percent |  |  | 80.00% |  |  |
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 |  |  |
U.S. | BIG | Public finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | $ 3,796 | $ 5,372 |  |
U.S. | BIG | RMBS |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 1,010 | 1,265 |  |
Non U.S. |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 45,394 |  |  |
Non U.S. | Public finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | 44,463 | 49,945 |  |
Net Expected Loss to be Paid (Recovered) |  |  | 9 | 12 | 36 | $ 23
Economic benefit for public finance transactions |  |  | 2 | 22 | $ (13) |
Non U.S. | BIG | Public finance |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |
Net Par Outstanding |  |  | $ 981 | $ 600 |  |

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- 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
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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 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 Represents the number of payments by which a mortgage borrower may be behind and still be considered a performing borrower. + References No definition available. + Details
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- Definition Period of Maximum Missed Payments to be Classified as Performing Borrower + 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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