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Contracts Accounted for as Insurance - Loss and LAE Reported on the Statements of Operations (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | $ 16 | $ (220) | $ 203
Public finance | Financial Guarantee Insurance And Other Product Line | Consolidated Entity Excluding Variable Interest Entities (VIE) |  |  |
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | 125 | (155) | 230
Public finance | Financial Guarantee Insurance And Other Product Line | Consolidated Entity Excluding Variable Interest Entities (VIE) | U.S. |  |  |
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | 125 | (146) | 225
Public finance | Financial Guarantee Insurance And Other Product Line | Consolidated Entity Excluding Variable Interest Entities (VIE) | Non U.S. |  |  |
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | 0 | (9) | 5
RMBS | Financial Guarantee Insurance And Other Product Line | Consolidated Entity Excluding Variable Interest Entities (VIE) | U.S. |  |  |
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | (112) | (69) | (34)
Other structured finance | Financial Guarantee Insurance And Other Product Line | Consolidated Entity Excluding Variable Interest Entities (VIE) |  |  |
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | 3 | 4 | 7
Structured finance | Financial Guarantee Insurance And Other Product Line | Consolidated Entity Excluding Variable Interest Entities (VIE) |  |  |
Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Line Items] |  |  |
Loss and LAE (benefit) | $ (109) | $ (65) | $ (27)

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- Definition [Line Items] for Liability for Claims and Claims Adjustment Expense Including Salvage and Subrogation Recoverable [Table] + References No definition available. + Details
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- Definition Amount, after effects of policies assumed or ceded, of expense related to the provision for policy benefits and costs incurred. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 220 -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-04.5) -URI https://asc.fasb.org/extlink&oid=120400993&loc=SL114874131-224263 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 944 -SubTopic 20 -Section 50 -Paragraph 3 -URI https://asc.fasb.org/extlink&oid=99397103&loc=d3e6811-158387 + Details
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