Insurance (Liabilities for Guarantees) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	$ 6,441	$ 5,548	$ 5,127
Incurred guaranteed benefits	226	1,063	485
Paid guaranteed benefits	(185)	(170)	(64)
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	(32)
Balance at December 31,	6,450	6,441	5,548
Variable Annuity Guarantees: | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	639	465	428
Incurred guaranteed benefits	133	195	62
Paid guaranteed benefits	(29)	(21)	(25)
Balance at December 31,	743	639	465
Variable Annuity Guarantees: | Guaranteed Minimum Death and Withdrawal Benefit [Member] | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Variable Annuity Guarantees: | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	1,129	894	898
Incurred guaranteed benefits	87	240	(3)
Paid guaranteed benefits	(7)	(5)	(1)
Balance at December 31,	1,177	1,129	894
Variable Annuity Guarantees: | Guaranteed Minimum Income Benefit | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	(32)
Universal and Variable Life Contracts | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	4,265	3,762	3,442
Incurred guaranteed benefits	(37)	602	358
Paid guaranteed benefits	(102)	(99)	(38)
Balance at December 31,	4,126	4,265	3,762
Universal and Variable Life Contracts | Secondary Guarantees | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Universal and Variable Life Contracts | Secondary Guarantees | Foreign Currency Translation
Movement In Guaranteed Benefit Liability Gross Rollforward
Incurred guaranteed benefits	(260)	125	23
Universal and Variable Life Contracts | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	408	427	359
Incurred guaranteed benefits	43	26	68
Paid guaranteed benefits	(47)	(45)	0
Balance at December 31,	404	408	427
Universal and Variable Life Contracts | Paid-Up Guarantees | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Ceded
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	724	640	530
Incurred guaranteed benefits	83	125	106
Paid guaranteed benefits	(59)	(41)	4
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Balance at December 31,	748	724	640
Ceded | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	427	349	269
Incurred guaranteed benefits	57	96	80
Paid guaranteed benefits	(33)	(18)	0
Balance at December 31,	451	427	349
Ceded | Secondary Guarantees | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Ceded | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	292	281	251
Incurred guaranteed benefits	30	43	30
Paid guaranteed benefits	(34)	(32)	0
Balance at December 31,	288	292	281
Ceded | Paid-Up Guarantees | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Ceded | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	(2)	0	0
Incurred guaranteed benefits	(6)	(11)	(4)
Paid guaranteed benefits	8	9	4
Balance at December 31,	0	(2)	0
Ceded | Guaranteed Minimum Death and Withdrawal Benefit [Member] | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Ceded | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	7	10	10
Incurred guaranteed benefits	2	(3)	0
Paid guaranteed benefits	0	0	0
Balance at December 31,	9	7	10
Ceded | Guaranteed Minimum Income Benefit | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Net
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	5,717	4,908	4,597
Incurred guaranteed benefits	143	938	379
Paid guaranteed benefits	(126)	(129)	(68)
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	(32)
Balance at December 31,	5,702	5,717	4,908
Net | Secondary Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	3,838	3,413	3,173
Incurred guaranteed benefits	(94)	506	278
Paid guaranteed benefits	(69)	(81)	(38)
Balance at December 31,	3,675	3,838	3,413
Net | Secondary Guarantees | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Net | Paid-Up Guarantees
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	116	146	108
Incurred guaranteed benefits	13	(17)	38
Paid guaranteed benefits	(13)	(13)	0
Balance at December 31,	116	116	146
Net | Paid-Up Guarantees | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Net | Guaranteed Minimum Death and Withdrawal Benefit [Member]
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	641	465	428
Incurred guaranteed benefits	139	206	66
Paid guaranteed benefits	(37)	(30)	(29)
Balance at December 31,	743	641	465
Net | Guaranteed Minimum Death and Withdrawal Benefit [Member] | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	0
Net | Guaranteed Minimum Income Benefit
Movement In Guaranteed Benefit Liability Gross Rollforward
Balance at January 1,	1,122	884	888
Incurred guaranteed benefits	85	243	(3)
Paid guaranteed benefits	(7)	(5)	(1)
Balance at December 31,	1,168	$ 1,122	$ 884
Net | Guaranteed Minimum Income Benefit | MetLife Poland and Greece
Movement In Guaranteed Benefit Liability Gross Rollforward
Liabilities for Guarantees on Long-Duration Contracts, Other Liability Adjustments	$ (32)