Investments - Net Realized Investment Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Investments, Debt and Equity Securities [Abstract]
Gross realized gains on sales of available-for-sale securities	$ 2	$ 0	$ 21	$ 0
Gross realized losses on sales available-for-sale securities	(1)	(10)	(16)	(33)
Net foreign currency gains (losses)	(1)	0	(1)	(3)
Change in allowance for credit losses and intent to sell	(8)	(4)	(23)	(13)
Other net realized gains (losses)	(1)	0	(1)	10
Net realized investment gains (losses)	$ (9)	$ (14)	$ (20)	$ (39)