Reserves for Insurance Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Dec. 31, 2023	Dec. 31, 2022
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Total gross reserves for insurance losses and loss adjustment expenses, beginning balance			$ 140	$ 119
Less: Reinsurance recoverable			66	72
Net reserves for insurance losses and loss adjustment expenses	$ 119	$ 68	119	68	$ 74	$ 47
Current year			411	326
Prior years			17	3
Total net insurance losses and loss adjustment expenses incurred	135	107	428	329
Current year			(319)	(270)
Prior years			(64)	(38)
Total net insurance losses and loss adjustment expenses paid or payable			(383)	(308)
Plus: Reinsurance recoverable	78	77	78	77
Total gross reserves for insurance losses and loss adjustment expenses, ending balance	$ 197	$ 145	$ 197	$ 145