Investments - Schedule of Gross Realized Gains (Losses) on Sales of Fixed Income Securities (Details) - Fixed income securities - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Debt Securities, Available-for-Sale [Line Items]
Gross realized gains	$ 11	$ 19	$ 85	$ 112
Gross realized losses	$ (133)	$ (181)	$ (459)	$ (748)