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%