Junior Subordinated Debt Securities (Junior Subordinated Debt Securities) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (108)	$ (87)
Junior Subordinated Notes	3,161	3,158
MetLife Inc $500M Maturing 2069 [Member]
Debt Instrument [Line Items]
Face Value	500	500
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (5)	(5)
Debt Instrument, Interest Rate, Stated Percentage	10.75%
Debt Instrument, Interest Rate Terms	SOFR + 0.26161% + 7.548%
Junior Subordinated Notes	$ 495	495
Senior notes
Debt Instrument [Line Items]
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (106)	(83)
Debt Instrument, Interest Rate, Stated Percentage	5.70%
MetLife Capital Trust X $750M Maturing 2068 [Member]
Debt Instrument [Line Items]
Face Value	$ 750	750
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (8)	(9)
Debt Instrument, Interest Rate, Stated Percentage	9.25%
Debt Instrument, Interest Rate Terms	SOFR + 0.26161% + 5.540%
Junior Subordinated Notes	$ 742	741
MetLife Capital Trust IV $700M Maturing 2067 [Member]
Debt Instrument [Line Items]
Face Value	700	700
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (12)	(13)
Debt Instrument, Interest Rate, Stated Percentage	7.875%
Debt Instrument, Interest Rate Terms	SOFR + 0.26161% + 3.960%
Junior Subordinated Notes	$ 688	687
MetLife Inc $1,250M Maturing 2066 [Member]
Debt Instrument [Line Items]
Face Value	1,250	1,250
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (14)	(15)
Debt Instrument, Interest Rate, Stated Percentage	6.40%
Debt Instrument, Interest Rate Terms	SOFR + 0.26161% + 2.205%
Junior Subordinated Notes	$ 1,236	1,235
Junior Subordinated Debt [Member]
Debt Instrument [Line Items]
Face Value	3,200	3,200
Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net	$ (39)	$ (42)

Face (par) amount of debt instrument at time of issuance.

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Including the current and noncurrent portions, carrying value as of the balance sheet date of long-term debt (with maturities initially due after one year or beyond the operating cycle if longer) identified as Junior Subordinated Notes, which have a lower priority than senior instruments.

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