Segment Information (Earnings) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Revenues
Premiums	$ 42,009	$ 42,034	$ 42,235
Universal life and investment-type product policy fees	5,756	5,603	5,603
Net investment income	21,395	17,117	18,868
Other revenues	2,619	1,849	1,842
Net investment gains (losses)	1,529	(110)	444
Net derivative gains (losses)	(2,228)	1,349	628
Total revenues	71,080	67,842	69,620
Expenses
Policyholder benefits and claims and policyholder dividends	44,830	42,551	42,672
Interest credited to policyholder account balances	5,538	5,214	6,464
Capitalization of DAC	(2,718)	(3,013)	(3,358)
Amortization of DAC and VOBA	2,555	3,160	2,896
Amortization of negative VOBA	(34)	(45)	(33)
Interest expense on debt	920	913	955
Other expenses	11,863	12,135	13,229
Total expenses	62,954	60,915	62,825
Provision for income tax expense (benefit)	1,551	1,509	886
Net income (loss)	6,575	5,418	5,909
U.S.
Expenses
Amortization of DAC and VOBA	158	471	475
Asia
Expenses
Amortization of DAC and VOBA	1,404	1,468	1,380
Latin America
Expenses
Amortization of DAC and VOBA	285	276	291
EMEA
Expenses
Amortization of DAC and VOBA	382	452	420
MetLife Holdings
Expenses
Amortization of DAC and VOBA	317	485	324
Corporate & Other
Expenses
Amortization of DAC and VOBA	9	8	6
Operating Segments
Revenues
Premiums	41,027	41,982	42,164
Universal life and investment-type product policy fees	5,561	5,465	5,395
Net investment income	21,280	17,328	17,830
Other revenues	2,376	1,690	1,585
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	70,244	66,465	66,974
Expenses
Policyholder benefits and claims and policyholder dividends	43,651	41,859	42,192
Interest credited to policyholder account balances	4,592	4,673	5,029
Capitalization of DAC	(2,599)	(3,008)	(3,338)
Amortization of DAC and VOBA	2,336	2,994	2,787
Amortization of negative VOBA	(34)	(45)	(33)
Interest expense on debt	919	913	955
Other expenses	11,299	11,872	12,778
Total expenses	60,164	59,258	60,370
Provision for income tax expense (benefit)	1,931	1,382	659
Adjusted earnings	8,149	5,825	5,945
Operating Segments | U.S.
Revenues
Premiums	26,358	27,265	26,801
Universal life and investment-type product policy fees	1,140	1,070	1,078
Net investment income	8,048	6,903	7,021
Other revenues	1,538	957	887
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	37,084	36,195	35,787
Expenses
Policyholder benefits and claims and policyholder dividends	27,957	26,309	26,165
Interest credited to policyholder account balances	1,422	1,622	1,984
Capitalization of DAC	(65)	(453)	(484)
Amortization of DAC and VOBA	60	471	475
Amortization of negative VOBA	0	0	0
Interest expense on debt	7	7	10
Other expenses	3,632	4,162	4,075
Total expenses	33,013	32,118	32,225
Provision for income tax expense (benefit)	850	853	724
Adjusted earnings	3,221	3,224	2,838
Operating Segments | Asia
Revenues
Premiums	6,421	6,571	6,632
Universal life and investment-type product policy fees	1,814	1,892	1,674
Net investment income	5,052	3,938	3,691
Other revenues	73	61	56
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	13,360	12,462	12,053
Expenses
Policyholder benefits and claims and policyholder dividends	5,008	5,213	5,185
Interest credited to policyholder account balances	1,995	1,834	1,710
Capitalization of DAC	(1,607)	(1,652)	(1,913)
Amortization of DAC and VOBA	1,369	1,415	1,288
Amortization of negative VOBA	(27)	(37)	(25)
Interest expense on debt	0	0	0
Other expenses	3,388	3,481	3,818
Total expenses	10,126	10,254	10,063
Provision for income tax expense (benefit)	936	643	585
Adjusted earnings	2,298	1,565	1,405
Operating Segments | Latin America
Revenues
Premiums	2,609	2,265	2,723
Universal life and investment-type product policy fees	1,109	994	1,094
Net investment income	1,271	992	1,271
Other revenues	41	38	44
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	5,030	4,289	5,132
Expenses
Policyholder benefits and claims and policyholder dividends	3,143	2,406	2,623
Interest credited to policyholder account balances	249	240	332
Capitalization of DAC	(414)	(362)	(396)
Amortization of DAC and VOBA	285	276	291
Amortization of negative VOBA	0	0	0
Interest expense on debt	5	4	3
Other expenses	1,401	1,318	1,443
Total expenses	4,669	3,882	4,296
Provision for income tax expense (benefit)	70	127	227
Adjusted earnings	291	280	609
Operating Segments | EMEA
Revenues
Premiums	2,271	2,259	2,177
Universal life and investment-type product policy fees	395	433	423
Net investment income	215	269	291
Other revenues	47	52	54
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	2,928	3,013	2,945
Expenses
Policyholder benefits and claims and policyholder dividends	1,241	1,196	1,176
Interest credited to policyholder account balances	86	109	98
Capitalization of DAC	(469)	(491)	(505)
Amortization of DAC and VOBA	356	454	428
Amortization of negative VOBA	(7)	(8)	(8)
Interest expense on debt	0	1	0
Other expenses	1,324	1,344	1,399
Total expenses	2,531	2,605	2,588
Provision for income tax expense (benefit)	96	81	75
Adjusted earnings	301	327	282
Operating Segments | MetLife Holdings
Revenues
Premiums	3,333	3,600	3,748
Universal life and investment-type product policy fees	1,101	1,073	1,124
Net investment income	6,450	5,184	5,281
Other revenues	257	238	253
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	11,141	10,095	10,406
Expenses
Policyholder benefits and claims and policyholder dividends	6,268	6,738	6,970
Interest credited to policyholder account balances	840	868	905
Capitalization of DAC	(33)	(39)	(28)
Amortization of DAC and VOBA	257	370	299
Amortization of negative VOBA	0	0	0
Interest expense on debt	5	6	8
Other expenses	992	942	969
Total expenses	8,329	8,885	9,123
Provision for income tax expense (benefit)	570	234	249
Adjusted earnings	2,242	976	1,034
Operating Segments | Corporate & Other
Revenues
Premiums	35	22	83
Universal life and investment-type product policy fees	2	3	2
Net investment income	244	42	275
Other revenues	420	344	291
Net investment gains (losses)	0	0	0
Net derivative gains (losses)	0	0	0
Total revenues	701	411	651
Expenses
Policyholder benefits and claims and policyholder dividends	34	(3)	73
Interest credited to policyholder account balances	0	0	0
Capitalization of DAC	(11)	(11)	(12)
Amortization of DAC and VOBA	9	8	6
Amortization of negative VOBA	0	0	0
Interest expense on debt	902	895	934
Other expenses	562	625	1,074
Total expenses	1,496	1,514	2,075
Provision for income tax expense (benefit)	(591)	(556)	(1,201)
Adjusted earnings	(204)	(547)	(223)
Significant Reconciling Items
Revenues
Premiums	982	52	71
Universal life and investment-type product policy fees	195	138	208
Net investment income	115	(211)	1,038
Other revenues	243	159	257
Net investment gains (losses)	1,529	(110)	444
Net derivative gains (losses)	(2,228)	1,349	628
Total revenues	836	1,377	2,646
Expenses
Policyholder benefits and claims and policyholder dividends	1,179	692	480
Interest credited to policyholder account balances	946	541	1,435
Capitalization of DAC	(119)	(5)	(20)
Amortization of DAC and VOBA	219	166	109
Amortization of negative VOBA	0	0	0
Interest expense on debt	1	0	0
Other expenses	564	263	451
Total expenses	2,790	1,657	2,455
Provision for income tax expense (benefit)	$ (380)	$ 127	$ 227