Investments - Investment Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Fixed maturity securities:
Investment gains (losses)	$ (18)	$ (9)
Nonredeemable Preferred Stock
Fixed maturity securities:
Investment gains (losses)	(5)	(2)
Fixed maturity securities
Fixed maturity securities:
Gross gains	6	13
Gross losses	(20)	(22)
Investment gains (losses)	(14)	(9)
Equity securities
Fixed maturity securities:
Investment gains (losses)	$ (4)