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Business and Basis of Presentation - Additional Information (Details) $ in Millions |  | 1 Months Ended | 3 Months Ended | 9 Months Ended
--- | --- | --- | --- | ---
Jul. 01, 2023 rISK | May 31, 2024 USD ($) | Sep. 30, 2024 USD ($) Company | Sep. 30, 2023 USD ($) | Sep. 30, 2023 USD ($)
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Number of holding companies with outstanding public debt | Company |  |  | 2 |  |
Assured Guaranty Municipal Corp. |  |  |  |  |
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Stock redeemed or during period |  | $ 100 |  |  |
Insurance licenses, writeoff |  |  | $ 6 |  |
AGC |  |  |  |  |
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Stock redeemed or during period |  |  | 300 |  |
Proceeds in exchange for redemption of common stock |  |  | 167 |  |
Consolidated Investment Vehicles |  |  |  |  |
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Number of remaining CIVs | rISK | 3 |  |  |  |
Sound Point Agreement |  |  |  |  |
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Assets held for sale |  |  |  | $ 4,700 | $ 4,700
Liabilities held for sale |  |  |  | 4,400 | 4,400
Disposal Group, Held-for-sale, Not Discontinued Operations |  |  |  |  |
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Assets held for sale |  |  | 28 |  |
Liabilities held for sale |  |  | $ 3 |  |
Disposal Group, Held-for-sale, Not Discontinued Operations | Sound Point Agreement |  |  |  |  |
Long-Lived Assets Held-for-sale [Line Items] |  |  |  |  |
Participation percentage | 30.00% |  |  |  |
Term to make new investments |  |  | 2 years |  |
Term to reinvest all returns of capital | 15 years |  |  |  |
Expenses recognized |  |  |  | $ 14 | $ 46

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