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Outstanding Exposure - Financial Guaranty Portfolio by Asset Class (Details) - USD ($) $ in Millions | Dec. 31, 2023 | Aug. 31, 2023 | Dec. 31, 2022
--- | --- | --- | ---
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | $ 249,153 | $ 108 | $ 233,258
Public finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 239,296 |  | 224,099
Structured finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 9,857 |  | 9,159
U.S. |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 198,921 |  |
U.S. | Public finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 190,289 |  | 179,636
U.S. | Public finance | General obligation |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 74,609 |  | 71,868
U.S. | Public finance | Tax backed |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 33,060 |  | 33,752
U.S. | Public finance | Municipal utilities |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 29,300 |  | 26,436
U.S. | Public finance | Transportation |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 22,052 |  | 19,688
U.S. | Public finance | Healthcare |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 12,604 |  | 11,304
U.S. | Public finance | Infrastructure finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 8,796 |  | 6,955
U.S. | Public finance | Higher education |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 7,250 |  | 7,137
U.S. | Public finance | Housing revenue |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 1,152 |  | 959
U.S. | Public finance | Investor-owned utilities |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 329 |  | 332
U.S. | Public finance | Renewable energy |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 167 |  | 180
U.S. | Public finance | Other |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 970 |  | 1,025
U.S. | Structured finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 8,632 |  | 8,228
U.S. | Structured finance | Other |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 892 |  | 806
U.S. | Structured finance | Insurance securitizations |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 4,379 |  | 3,879
U.S. | Structured finance | RMBS |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 1,774 |  | 1,956
U.S. | Structured finance | Pooled corporate obligations |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 631 |  | 625
U.S. | Structured finance | Financial products |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 464 |  | 453
U.S. | Structured finance | Consumer receivables |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 314 |  | 437
U.S. | Structured finance | Subscription Finance Facilities |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 178 |  | 72
Non U.S. |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 50,232 |  |
Non U.S. | Public finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 49,007 |  | 44,463
Non U.S. | Public finance | Infrastructure finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 15,430 |  | 13,915
Non U.S. | Public finance | Renewable energy |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 2,030 |  | 2,086
Non U.S. | Public finance | Regulated utilities |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 20,545 |  | 17,855
Non U.S. | Public finance | Sovereign and sub-sovereign |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 9,869 |  | 9,526
Non U.S. | Public finance | Pooled infrastructure |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 1,133 |  | 1,081
Non U.S. | Structured finance |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 1,225 |  | 931
Non U.S. | Structured finance | Other |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 104 |  | 105
Non U.S. | Structured finance | RMBS |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 252 |  | 263
Non U.S. | Structured finance | Pooled corporate obligations |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | 425 |  | 344
Non U.S. | Structured finance | Subscription Finance Facilities |  |  |
Schedule of Insured Financial Obligations [Line Items] |  |  |
Total net par outstanding | $ 444 |  | $ 219

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