Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Revenues
Premiums	$ 11,230	$ 17,332	$ 32,497	$ 39,505
Universal life and investment-type product policy fees	1,334	1,275	3,911	3,959
Net investment income	4,825	3,585	14,542	11,452
Other revenues	606	728	1,866	2,003
Net investment gains (losses)	(927)	(411)	(2,650)	(1,610)
Net derivative gains (losses)	(1,202)	(226)	(2,289)	(2,147)
Total revenues	15,866	22,283	47,877	53,162
Expenses
Policyholder benefits and claims and policyholder dividends	11,283	17,761	33,274	40,943
Policyholder liability remeasurement (gains) losses	(17)	136	(42)	94
Market risk benefit remeasurement (gains) losses	(796)	(965)	(1,425)	(3,162)
Interest credited to policyholder account balances	1,658	1,014	5,455	2,167
Capitalization of DAC	(742)	(626)	(2,189)	(1,915)
Amortization of DAC and VOBA	499	441	1,448	1,374
Amortization of negative VOBA	(7)	(7)	(20)	(22)
Interest expense on debt	265	239	776	690
Other expenses	3,189	2,875	9,379	8,655
Total expenses	15,332	20,868	46,656	48,824
Provision for income tax expense (benefit)	39	248	233	617
Net income (loss)	495	1,167	988	3,721
Operating Segments [Member]
Revenues
Premiums	11,230	17,332	32,497	39,464
Universal life and investment-type product policy fees	1,334	1,275	3,911	3,948
Net investment income	5,056	4,163	14,702	13,659
Other revenues	617	688	1,887	1,865
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	18,237	23,458	52,997	58,936
Expenses
Policyholder benefits and claims and policyholder dividends	11,352	17,586	33,243	40,433
Policyholder liability remeasurement (gains) losses	(17)	136	(42)	94
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	1,705	1,352	4,889	3,796
Capitalization of DAC	(742)	(626)	(2,189)	(1,904)
Amortization of DAC and VOBA	499	441	1,448	1,366
Amortization of negative VOBA	(7)	(7)	(20)	(22)
Interest expense on debt	265	239	776	690
Other expenses	3,159	2,815	9,302	8,448
Total expenses	16,214	21,936	47,407	52,901
Provision for income tax expense (benefit)	468	358	1,261	1,346
Adjusted earnings	1,555	1,164	4,329	4,689
Segment Reconciling Items [Member]
Revenues
Premiums	0	0	0	41
Universal life and investment-type product policy fees	0	0	0	11
Net investment income	(231)	(578)	(160)	(2,207)
Other revenues	(11)	40	(21)	138
Net investment gains (losses)	(927)	(411)	(2,650)	(1,610)
Net derivative gains (losses)	(1,202)	(226)	(2,289)	(2,147)
Total revenues	(2,371)	(1,175)	(5,120)	(5,774)
Expenses
Policyholder benefits and claims and policyholder dividends	(69)	175	31	510
Policyholder liability remeasurement (gains) losses	0	0	0	0
Market risk benefit remeasurement (gains) losses	(796)	(965)	(1,425)	(3,162)
Interest credited to policyholder account balances	(47)	(338)	566	(1,629)
Capitalization of DAC	0	0	0	(11)
Amortization of DAC and VOBA	0	0	0	8
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	0	0	0	0
Other expenses	30	60	77	207
Total expenses	(882)	(1,068)	(751)	(4,077)
Provision for income tax expense (benefit)	(429)	(110)	(1,028)	(729)
U.S.
Expenses
Capitalization of DAC			(152)	(93)
U.S. | Operating Segments [Member]
Revenues
Premiums	7,606	13,954	21,666	29,053
Universal life and investment-type product policy fees	301	286	892	867
Net investment income	2,339	1,716	6,738	5,300
Other revenues	437	514	1,319	1,344
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	10,683	16,470	30,615	36,564
Expenses
Policyholder benefits and claims and policyholder dividends	7,692	13,978	22,218	29,510
Policyholder liability remeasurement (gains) losses	(105)	9	(147)	(21)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	806	548	2,248	1,407
Capitalization of DAC	(46)	(38)	(152)	(93)
Amortization of DAC and VOBA	19	17	55	49
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	3	3	11	6
Other expenses	1,075	1,003	3,249	2,931
Total expenses	9,444	15,520	27,482	33,789
Provision for income tax expense (benefit)	259	199	657	581
Adjusted earnings	980	751	2,476	2,194
Asia
Expenses
Capitalization of DAC			(1,202)	(1,120)
Asia | Operating Segments [Member]
Revenues
Premiums	1,312	1,346	3,999	4,291
Universal life and investment-type product policy fees	411	438	1,204	1,261
Net investment income	1,023	827	2,954	3,081
Other revenues	20	21	61	66
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,766	2,632	8,218	8,699
Expenses
Policyholder benefits and claims and policyholder dividends	1,095	1,119	3,282	3,513
Policyholder liability remeasurement (gains) losses	108	61	92	27
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	576	497	1,682	1,488
Capitalization of DAC	(404)	(351)	(1,202)	(1,120)
Amortization of DAC and VOBA	204	178	587	554
Amortization of negative VOBA	(6)	(6)	(17)	(18)
Interest expense on debt	0	0	0	0
Other expenses	788	749	2,373	2,349
Total expenses	2,361	2,247	6,797	6,793
Provision for income tax expense (benefit)	130	118	435	554
Adjusted earnings	275	267	986	1,352
Latin America
Expenses
Capitalization of DAC			(470)	(357)
Latin America | Operating Segments [Member]
Revenues
Premiums	1,116	822	3,164	2,382
Universal life and investment-type product policy fees	359	293	1,046	876
Net investment income	365	399	1,162	1,180
Other revenues	9	10	31	29
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	1,849	1,524	5,403	4,467
Expenses
Policyholder benefits and claims and policyholder dividends	1,020	872	2,962	2,464
Policyholder liability remeasurement (gains) losses	(4)	3	(5)	(5)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	106	89	310	241
Capitalization of DAC	(171)	(130)	(470)	(357)
Amortization of DAC and VOBA	121	104	344	305
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	2	3	8	10
Other expenses	493	380	1,388	1,093
Total expenses	1,567	1,321	4,537	3,751
Provision for income tax expense (benefit)	83	44	233	171
Adjusted earnings	199	159	633	545
EMEA
Expenses
Capitalization of DAC			(341)	(316)
EMEA | Operating Segments [Member]
Revenues
Premiums	502	472	1,497	1,474
Universal life and investment-type product policy fees	79	57	231	217
Net investment income	51	40	143	119
Other revenues	7	8	23	25
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	639	577	1,894	1,835
Expenses
Policyholder benefits and claims and policyholder dividends	230	235	728	737
Policyholder liability remeasurement (gains) losses	(9)	(11)	(10)	(1)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	19	16	54	53
Capitalization of DAC	(114)	(96)	(341)	(305)
Amortization of DAC and VOBA	87	75	257	242
Amortization of negative VOBA	(1)	(1)	(3)	(4)
Interest expense on debt	0	0	0	0
Other expenses	315	269	929	863
Total expenses	527	487	1,614	1,585
Provision for income tax expense (benefit)	24	26	62	65
Adjusted earnings	88	64	218	185
MetLife Holdings
Expenses
Capitalization of DAC			(17)	(22)
MetLife Holdings | Operating Segments [Member]
Revenues
Premiums	685	745	2,127	2,281
Universal life and investment-type product policy fees	184	202	537	726
Net investment income	1,153	1,103	3,450	3,764
Other revenues	41	39	143	106
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,063	2,089	6,257	6,877
Expenses
Policyholder benefits and claims and policyholder dividends	1,311	1,385	4,021	4,221
Policyholder liability remeasurement (gains) losses	(7)	74	28	94
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	198	202	595	607
Capitalization of DAC	(5)	(9)	(17)	(22)
Amortization of DAC and VOBA	65	64	197	209
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	4	2	10	5
Other expenses	238	228	707	706
Total expenses	1,804	1,946	5,541	5,820
Provision for income tax expense (benefit)	51	26	139	210
Adjusted earnings	208	117	577	847
Corporate & Other
Expenses
Capitalization of DAC			(7)	(7)
Corporate & Other | Operating Segments [Member]
Revenues
Premiums	9	(7)	44	(17)
Universal life and investment-type product policy fees	0	(1)	1	1
Net investment income	125	78	255	215
Other revenues	103	96	310	295
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	237	166	610	494
Expenses
Policyholder benefits and claims and policyholder dividends	4	(3)	32	(12)
Policyholder liability remeasurement (gains) losses	0	0	0	0
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	0	0	0	0
Capitalization of DAC	(2)	(2)	(7)	(7)
Amortization of DAC and VOBA	3	3	8	7
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	256	231	747	669
Other expenses	250	186	656	506
Total expenses	511	415	1,436	1,163
Provision for income tax expense (benefit)	(79)	(55)	(265)	(235)
Adjusted earnings	$ (195)	$ (194)	$ (561)	$ (434)