Investments (Supplemental Net Investment Gains (Losses)) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 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)	$ 11	$ (58)	$ 84	$ (47)
Realized gains (losses) on investments sold or disposed	22	(39)	(424)	(369)
Foreign currency gains (losses)	(9)	170	136	5
Net realized investment gains (losses) from sales and disposals of investments	114	26	(187)	(170)
Net investment income
Net Investment Income [Line Items]
Net realized investment gains (losses) from sales and disposals of investments	92	65	237	199
Cash Flow Hedging
Net Investment Income [Line Items]
Realized gains (losses) on investments sold or disposed	(26)	0	(17)	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)	$ 14	$ (36)	$ 51	$ (23)

Amount of realized gain (loss) on investment in debt and equity securities.

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