Investments (Supplemental Net Investment Gains (Losses)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Net Investment Income [Line Items]
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 30	$ 41
Foreign Currency Transaction Gain (Loss), Realized	(45)	41
Realized gains (losses) on investments sold or disposed (1)	(135)	(546)
Debt and Equity Securities, Realized Gain (Loss)	(67)	(508)
Net investment income
Net Investment Income [Line Items]
Debt and Equity Securities, Realized Gain (Loss)	68	38
Equity Securities
Net Investment Income [Line Items]
Equity Securities, FV-NI, Unrealized Gain (Loss)	$ 31	$ 40