Reserves for Insurance Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024	Dec. 31, 2024	Dec. 31, 2023
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Total gross reserves for insurance losses and loss adjustment expenses, beginning balance	$ 189	$ 140
Less: Reinsurance recoverable	60	66
Net reserves for insurance losses and loss adjustment expenses	192	87	$ 129	$ 74
Current year	161	103
Prior years	0	9
Total net insurance losses and loss adjustment expenses incurred	161	112
Current year	(44)	(57)
Prior years	(54)	(42)
Total net insurance losses and loss adjustment expenses paid or payable	(98)	(99)
Plus: Reinsurance recoverable	76	77
Total gross reserves for insurance losses and loss adjustment expenses, ending balance	$ 268	$ 164