Investments (Supplemental Net Investment Gains (Losses)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Net Investment Income [Line Items]
Changes in estimated fair value subsequent to purchase of equity securities still held at the end of the respective periods and recognized in net investment gains (losses)	$ 10	$ 30
Realized gains (losses) on investments sold or disposed	(301)	(135)
Foreign currency gains (losses)	75	(45)
Net realized investment gains (losses) from sales and disposals of investments	(258)	(67)
Net investment income
Net Investment Income [Line Items]
Net realized investment gains (losses) from sales and disposals of investments	43	68
Cash Flow Hedging
Net Investment Income [Line Items]
Realized gains (losses) on investments sold or disposed	(1)	0
Equity Securities
Net Investment Income [Line Items]
Changes in estimated fair value subsequent to purchase of equity securities still held at the end of the respective periods and recognized in net investment gains (losses)	$ (10)	$ 31