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Income Taxes - Narrative (Details) - USD ($) $ in Millions |  | 3 Months Ended | 12 Months Ended | 71 Months Ended |  |
--- | --- | --- | --- | --- | --- | ---
Jan. 01, 2024 | Dec. 31, 2023 | Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022 | Mar. 31, 2023 | Jan. 01, 2023 | Dec. 31, 2021
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Income tax expense (benefit) |  |  | $ 96 | $ (93) | $ 11 |  |  |
Deferred tax assets, operating loss carryforwards, domestic |  |  | 21 |  |  |  |  |
Deferred tax assets, operating loss carryforwards, foreign |  |  | $ 10 |  |  |  |  |
Decrease in valuation allowance |  |  |  |  | 19 |  |  |
Less: Valuation allowance |  | $ 0 |  | 0 | 5 |  | $ 2 | $ 24
Realization assessment period |  |  | 3 years |  |  |  |  |
Unrecognized tax benefits |  | 0 | $ 0 | 0 | 0 |  |  |
Income tax penalties and interest accrued |  | 0 | 0 | 0 | $ 0 |  |  |
Foreign Tax Credit Provision Adjustment |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Decrease in valuation allowance |  |  |  | 3 |  |  |  |
Foreign Tax Credit Change In Realization |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Decrease in valuation allowance |  |  |  | $ 2 |  |  |  |
CIFG Holding Inc. |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Operating loss carryforwards |  |  | $ 189 |  |  |  |  |
Foreign Tax Jurisdiction |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Income tax expense (benefit) |  | $ (189) |  |  |  |  |  |
Foreign Tax Jurisdiction | Minimum |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Income tax benefit, period of recognition |  | 10 years |  |  |  |  |  |
Foreign Tax Jurisdiction | Maximum |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Income tax benefit, period of recognition |  | 15 years |  |  |  |  |  |
U.S. |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Corporate tax rate |  |  | 21.00% | 21.00% | 21.00% |  |  |
France |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Corporate tax rate |  |  | 25.00% | 25.00% |  |  |  |
U.K. |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Corporate tax rate | 15.00% |  | 25.00% |  |  | 19.00% |  |
Bermuda |  |  |  |  |  |  |  |
Income Taxes [Line Items] |  |  |  |  |  |  |  |
Corporate tax rate |  |  | 0.00% | 0.00% |  |  |  |

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