Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Revenues
Premiums	$ 10,771	$ 10,327
Universal life and investment-type product policy fees	1,418	1,391
Net investment income	4,284	5,314
Other revenues	660	631
Net investment gains (losses)	(518)	134
Net derivative gains (losses)	(859)	(2,235)
Total revenues	15,756	15,562
Expenses
Policyholder benefits and claims and policyholder dividends	11,391	10,770
Interest credited to policyholder account balances	630	1,351
Capitalization of DAC	(650)	(775)
Amortization of DAC and VOBA	537	590
Amortization of negative VOBA	(9)	(9)
Interest expense on debt	225	228
Other expenses	2,917	3,116
Total expenses	15,041	15,271
Provision for income tax expense (benefit)	41	(72)
Net income (loss)	674	363
Operating Segments [Member]
Revenues
Premiums	10,730	9,462
Universal life and investment-type product policy fees	1,392	1,366
Net investment income	4,992	5,294
Other revenues	610	585
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	17,724	16,707
Expenses
Policyholder benefits and claims and policyholder dividends	11,356	10,106
Interest credited to policyholder account balances	1,132	1,141
Capitalization of DAC	(639)	(686)
Amortization of DAC and VOBA	546	508
Amortization of negative VOBA	(9)	(9)
Interest expense on debt	225	227
Other expenses	2,838	2,854
Total expenses	15,449	14,141
Provision for income tax expense (benefit)	485	533
Adjusted earnings	1,790	2,033
Segment Reconciling Items [Member]
Revenues
Premiums	41	865
Universal life and investment-type product policy fees	26	25
Net investment income	(708)	20
Other revenues	50	46
Net investment gains (losses)	(518)	134
Net derivative gains (losses)	(859)	(2,235)
Total revenues	(1,968)	(1,145)
Expenses
Policyholder benefits and claims and policyholder dividends	35	664
Interest credited to policyholder account balances	(502)	210
Capitalization of DAC	(11)	(89)
Amortization of DAC and VOBA	(9)	82
Amortization of negative VOBA	0	0
Interest expense on debt	0	1
Other expenses	79	262
Total expenses	(408)	1,130
Provision for income tax expense (benefit)	(444)	(605)
U.S. | Operating Segments [Member]
Revenues
Premiums	7,164	5,699
Universal life and investment-type product policy fees	297	297
Net investment income	1,874	2,010
Other revenues	426	396
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	9,761	8,402
Expenses
Policyholder benefits and claims and policyholder dividends	7,566	6,142
Interest credited to policyholder account balances	347	359
Capitalization of DAC	(23)	(18)
Amortization of DAC and VOBA	14	16
Amortization of negative VOBA	0	0
Interest expense on debt	2	1
Other expenses	979	911
Total expenses	8,885	7,411
Provision for income tax expense (benefit)	183	207
Adjusted earnings	693	784
Asia | Operating Segments [Member]
Revenues
Premiums	1,553	1,685
Universal life and investment-type product policy fees	448	458
Net investment income	1,242	1,264
Other revenues	21	18
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	3,264	3,425
Expenses
Policyholder benefits and claims and policyholder dividends	1,228	1,297
Interest credited to policyholder account balances	498	489
Capitalization of DAC	(392)	(435)
Amortization of DAC and VOBA	288	314
Amortization of negative VOBA	(8)	(7)
Interest expense on debt	0	0
Other expenses	837	899
Total expenses	2,451	2,557
Provision for income tax expense (benefit)	233	245
Adjusted earnings	580	623
Latin America | Operating Segments [Member]
Revenues
Premiums	732	595
Universal life and investment-type product policy fees	290	270
Net investment income	322	299
Other revenues	9	10
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	1,353	1,174
Expenses
Policyholder benefits and claims and policyholder dividends	769	761
Interest credited to policyholder account balances	68	59
Capitalization of DAC	(113)	(95)
Amortization of DAC and VOBA	80	60
Amortization of negative VOBA	0	0
Interest expense on debt	3	1
Other expenses	354	335
Total expenses	1,161	1,121
Provision for income tax expense (benefit)	50	13
Adjusted earnings	142	40
EMEA | Operating Segments [Member]
Revenues
Premiums	509	598
Universal life and investment-type product policy fees	88	67
Net investment income	41	63
Other revenues	9	13
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	647	741
Expenses
Policyholder benefits and claims and policyholder dividends	282	343
Interest credited to policyholder account balances	17	24
Capitalization of DAC	(101)	(127)
Amortization of DAC and VOBA	86	62
Amortization of negative VOBA	(1)	(2)
Interest expense on debt	0	0
Other expenses	296	349
Total expenses	579	649
Provision for income tax expense (benefit)	16	21
Adjusted earnings	52	71
MetLife Holdings | Operating Segments [Member]
Revenues
Premiums	776	827
Universal life and investment-type product policy fees	269	274
Net investment income	1,409	1,646
Other revenues	44	62
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	2,498	2,809
Expenses
Policyholder benefits and claims and policyholder dividends	1,518	1,523
Interest credited to policyholder account balances	202	210
Capitalization of DAC	(7)	(8)
Amortization of DAC and VOBA	76	54
Amortization of negative VOBA	0	0
Interest expense on debt	1	1
Other expenses	236	253
Total expenses	2,026	2,033
Provision for income tax expense (benefit)	95	158
Adjusted earnings	377	618
Corporate & Other | Operating Segments [Member]
Revenues
Premiums	(4)	58
Universal life and investment-type product policy fees	0	0
Net investment income	104	12
Other revenues	101	86
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	201	156
Expenses
Policyholder benefits and claims and policyholder dividends	(7)	40
Interest credited to policyholder account balances	0	0
Capitalization of DAC	(3)	(3)
Amortization of DAC and VOBA	2	2
Amortization of negative VOBA	0	0
Interest expense on debt	219	224
Other expenses	136	107
Total expenses	347	370
Provision for income tax expense (benefit)	(92)	(111)
Adjusted earnings	$ (54)	$ (103)