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, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Debt Securities, Available-for-Sale [Line Items]
Gross realized gains	$ 142	$ 201	$ 329	$ 275
Gross realized losses	$ (35)	$ (93)	$ (600)	$ (363)