Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2022	Jun. 30, 2021
Revenues
Premiums	$ 11,721		$ 9,132		$ 22,492	$ 19,459
Universal life and investment-type product policy fees	1,516		1,422		2,934	2,813
Net investment income	3,583		5,280		7,867	10,594
Other revenues	616		664		1,276	1,295
Net investment gains (losses)	(685)		1,605		(1,203)	1,739
Net derivative gains (losses)	(1,195)		421		(2,054)	(1,814)
Total revenues	15,556		18,524		31,312	34,086
Expenses
Policyholder benefits and claims and policyholder dividends	11,983		9,641		23,374	20,411
Interest credited to policyholder account balances	492		1,515		1,122	2,866
Capitalization of DAC	(622)		(642)		(1,272)	(1,417)
Amortization of DAC and VOBA	616		537		1,153	1,127
Amortization of negative VOBA	(10)		(10)		(19)	(19)
Interest expense on debt	226		228		451	456
Other expenses	2,873		2,768		5,790	5,884
Total expenses	15,558		14,037		30,599	29,308
Provision for income tax expense (benefit)	(140)		1,075		(99)	1,003
Net income (loss)	138	$ 674	3,412	$ 363	812	3,775
Operating Segments [Member]
Revenues
Premiums	11,721		9,132		22,451	18,594
Universal life and investment-type product policy fees	1,505		1,386		2,897	2,752
Net investment income	4,504		5,117		9,496	10,411
Other revenues	568		604		1,178	1,189
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	18,298		16,239		36,022	32,946
Expenses
Policyholder benefits and claims and policyholder dividends	11,984		9,565		23,340	19,671
Interest credited to policyholder account balances	1,187		1,150		2,319	2,291
Capitalization of DAC	(622)		(642)		(1,261)	(1,328)
Amortization of DAC and VOBA	596		540		1,142	1,048
Amortization of negative VOBA	(10)		(10)		(19)	(19)
Interest expense on debt	226		228		451	455
Other expenses	2,806		2,700		5,644	5,554
Total expenses	16,167		13,531		31,616	27,672
Provision for income tax expense (benefit)	476		584		961	1,117
Adjusted earnings	1,655		2,124		3,445	4,157
Segment Reconciling Items [Member]
Revenues
Premiums	0		0		41	865
Universal life and investment-type product policy fees	11		36		37	61
Net investment income	(921)		163		(1,629)	183
Other revenues	48		60		98	106
Net investment gains (losses)	(685)		1,605		(1,203)	1,739
Net derivative gains (losses)	(1,195)		421		(2,054)	(1,814)
Total revenues	(2,742)		2,285		(4,710)	1,140
Expenses
Policyholder benefits and claims and policyholder dividends	(1)		76		34	740
Interest credited to policyholder account balances	(695)		365		(1,197)	575
Capitalization of DAC	0		0		(11)	(89)
Amortization of DAC and VOBA	20		(3)		11	79
Amortization of negative VOBA	0		0		0	0
Interest expense on debt	0		0		0	1
Other expenses	67		68		146	330
Total expenses	(609)		506		(1,017)	1,636
Provision for income tax expense (benefit)	(616)		491		(1,060)	(114)
U.S. | Operating Segments [Member]
Revenues
Premiums	8,254		5,474		15,418	11,173
Universal life and investment-type product policy fees	284		282		581	579
Net investment income	1,710		1,998		3,584	4,008
Other revenues	405		380		831	776
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	10,653		8,134		20,414	16,536
Expenses
Policyholder benefits and claims and policyholder dividends	8,320		5,739		15,886	11,881
Interest credited to policyholder account balances	387		359		734	718
Capitalization of DAC	(14)		(13)		(37)	(31)
Amortization of DAC and VOBA	14		8		28	24
Amortization of negative VOBA	0		0		0	0
Interest expense on debt	1		2		3	3
Other expenses	949		898		1,928	1,809
Total expenses	9,657		6,993		18,542	14,404
Provision for income tax expense (benefit)	208		239		391	446
Adjusted earnings	788		902		1,481	1,686
Asia | Operating Segments [Member]
Revenues
Premiums	1,395		1,582		2,948	3,267
Universal life and investment-type product policy fees	498		436		946	894
Net investment income	1,012		1,158		2,254	2,422
Other revenues	24		19		45	37
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	2,929		3,195		6,193	6,620
Expenses
Policyholder benefits and claims and policyholder dividends	1,185		1,233		2,413	2,530
Interest credited to policyholder account balances	493		496		991	985
Capitalization of DAC	(370)		(395)		(762)	(830)
Amortization of DAC and VOBA	321		296		609	610
Amortization of negative VOBA	(8)		(8)		(16)	(15)
Interest expense on debt	0		0		0	0
Other expenses	763		832		1,600	1,731
Total expenses	2,384		2,454		4,835	5,011
Provision for income tax expense (benefit)	159		221		392	466
Adjusted earnings	386		520		966	1,143
Latin America | Operating Segments [Member]
Revenues
Premiums	826		636		1,558	1,231
Universal life and investment-type product policy fees	296		287		586	557
Net investment income	459		308		781	607
Other revenues	10		11		19	21
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	1,591		1,242		2,944	2,416
Expenses
Policyholder benefits and claims and policyholder dividends	811		724		1,580	1,485
Interest credited to policyholder account balances	84		60		152	119
Capitalization of DAC	(120)		(100)		(233)	(195)
Amortization of DAC and VOBA	90		83		170	143
Amortization of negative VOBA	0		0		0	0
Interest expense on debt	4		1		7	2
Other expenses	370		343		724	678
Total expenses	1,239		1,111		2,400	2,232
Provision for income tax expense (benefit)	85		34		135	47
Adjusted earnings	267		97		409	137
EMEA | Operating Segments [Member]
Revenues
Premiums	492		621		1,001	1,219
Universal life and investment-type product policy fees	86		107		174	174
Net investment income	38		62		79	125
Other revenues	8		16		17	29
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	624		806		1,271	1,547
Expenses
Policyholder benefits and claims and policyholder dividends	237		333		519	676
Interest credited to policyholder account balances	20		25		37	49
Capitalization of DAC	(108)		(122)		(209)	(249)
Amortization of DAC and VOBA	95		94		181	156
Amortization of negative VOBA	(2)		(2)		(3)	(4)
Interest expense on debt	0		0		0	0
Other expenses	298		349		594	698
Total expenses	540		677		1,119	1,326
Provision for income tax expense (benefit)	20		35		36	56
Adjusted earnings	64		94		116	165
MetLife Holdings | Operating Segments [Member]
Revenues
Premiums	760		839		1,536	1,666
Universal life and investment-type product policy fees	339		273		608	547
Net investment income	1,280		1,543		2,689	3,189
Other revenues	23		69		67	131
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	2,402		2,724		4,900	5,533
Expenses
Policyholder benefits and claims and policyholder dividends	1,433		1,549		2,951	3,072
Interest credited to policyholder account balances	203		210		405	420
Capitalization of DAC	(8)		(9)		(15)	(17)
Amortization of DAC and VOBA	74		56		150	110
Amortization of negative VOBA	0		0		0	0
Interest expense on debt	2		2		3	3
Other expenses	242		244		478	497
Total expenses	1,946		2,052		3,972	4,085
Provision for income tax expense (benefit)	92		136		187	294
Adjusted earnings	364		536		741	1,154
Corporate & Other | Operating Segments [Member]
Revenues
Premiums	(6)		(20)		(10)	38
Universal life and investment-type product policy fees	2		1		2	1
Net investment income	5		48		109	60
Other revenues	98		109		199	195
Net investment gains (losses)	0		0		0	0
Net derivative gains (losses)	0		0		0	0
Total revenues	99		138		300	294
Expenses
Policyholder benefits and claims and policyholder dividends	(2)		(13)		(9)	27
Interest credited to policyholder account balances	0		0		0	0
Capitalization of DAC	(2)		(3)		(5)	(6)
Amortization of DAC and VOBA	2		3		4	5
Amortization of negative VOBA	0		0		0	0
Interest expense on debt	219		223		438	447
Other expenses	184		34		320	141
Total expenses	401		244		748	614
Provision for income tax expense (benefit)	(88)		(81)		(180)	(192)
Adjusted earnings	$ (214)		$ (25)		$ (268)	$ (128)