Investments (Supplemental Net Investment Income) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Net Investment Income [Line Items]
Debt and Equity Securities, Realized Gain (Loss)	$ 32	$ (43)	$ (39)	$ (301)
Equity Securities, FV-NI, Unrealized Gain (Loss)	16	63	7	73
Income (Loss) from Equity Method Investments	282	238	815	505
Income Statement Location [Axis]: met:FVOSecuritiesAndUnitLinkedInvestmentMember
Net Investment Income [Line Items]
Debt and Equity Securities, Realized Gain (Loss)	270	102	441	145
Unit-linked investments
Net Investment Income [Line Items]
Equity Securities, FV-NI, Unrealized Gain (Loss)	988	532	595	248
FVO Securities and Unit linked Investments [Member]
Net Investment Income [Line Items]
Debt and Equity Securities, Unrealized Gain (Loss)	814	452	265	163
Debt and Equity Securities, Gain (Loss)	$ 1,084	$ 554	$ 706	$ 308

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

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