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Business and Basis of Presentation - Narrative (Details) $ in Millions |  | 1 Months Ended | 3 Months Ended | 12 Months Ended
--- | --- | --- | --- | ---
Jul. 01, 2023 USD ($) consolidatedInvestmentVehicle | May 31, 2024 USD ($) | Dec. 31, 2024 USD ($) Company | Sep. 30, 2024 USD ($) | Dec. 31, 2024 USD ($) Company | Dec. 31, 2023 USD ($)
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Number of holding companies having outstanding public debt | Company |  |  | 2 |  | 2 |
Assured Guaranty Municipal Corp. |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Insurance licenses, writeoff |  |  |  | $ 6 |  |
Stock redeemed or during period |  | $ 100 |  |  |  |
AG (U.S. domiciled) |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Stock redeemed or during period |  |  |  | 300 |  |
Proceeds in exchange for redemption of common stock |  |  |  | $ 167 |  |
Consolidated investment vehicles |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Number of remaining entities | consolidatedInvestmentVehicle | 3 |  |  |  |  |
Sound Point Agreement |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Assets |  |  |  |  |  | $ 4,700
Liabilities |  |  |  |  |  | 4,400
Disposal Group, Held-for-Sale, Not Discontinued Operations |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Assets |  |  | $ 28 |  | $ 28 |
Liabilities |  |  | $ 3 |  | 3 |
Disposal Group, Held-for-Sale, Not Discontinued Operations | Sound Point Agreement |  |  |  |  |  |
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] |  |  |  |  |  |
Consideration, equity interest, ownership percentage | 30.00% |  |  |  |  |
Term to make new investments | 2 years |  | 2 years |  |  |
Investment management commitment | $ 1,000 |  |  |  | $ 1,000 |
Term to reinvest all returns of capital | 15 years |  |  |  |  |
Operating expense |  |  |  |  |  | $ 46

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