Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Revenues
Premiums	$ 11,678	$ 11,556	$ 21,267	$ 22,173
Universal life and investment-type product policy fees	1,288	1,372	2,577	2,684
Net investment income	5,072	3,583	9,717	7,867
Other revenues	621	615	1,260	1,275
Net investment gains (losses)	(1,039)	(682)	(1,723)	(1,199)
Net derivative gains (losses)	(997)	(970)	(1,087)	(1,921)
Total revenues	16,623	15,474	32,011	30,879
Expenses
Policyholder benefits and claims and policyholder dividends	11,960	11,809	21,991	23,182
Policyholder liability remeasurement (gains) losses	(16)	(1)	(25)	(42)
Market risk benefit remeasurement (gains) losses	(817)	(757)	(629)	(2,197)
Interest credited to policyholder account balances	1,933	527	3,797	1,153
Capitalization of DAC	(729)	(637)	(1,447)	(1,289)
Amortization of DAC and VOBA	479	458	949	933
Amortization of negative VOBA	(6)	(7)	(13)	(15)
Interest expense on debt	256	226	511	451
Other expenses	3,133	2,868	6,190	5,780
Total expenses	16,193	14,486	31,324	27,956
Provision for income tax expense (benefit)	22	73	194	369
Net income (loss)	408	915	493	2,554
Operating Segments [Member]
Revenues
Premiums	11,678	11,556	21,267	22,132
Universal life and investment-type product policy fees	1,288	1,372	2,577	2,673
Net investment income	5,040	4,504	9,646	9,496
Other revenues	628	567	1,270	1,177
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	18,634	17,999	34,760	35,478
Expenses
Policyholder benefits and claims and policyholder dividends	11,930	11,628	21,891	22,847
Policyholder liability remeasurement (gains) losses	(16)	(1)	(25)	(42)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	1,642	1,253	3,184	2,444
Capitalization of DAC	(729)	(637)	(1,447)	(1,278)
Amortization of DAC and VOBA	479	458	949	925
Amortization of negative VOBA	(6)	(7)	(13)	(15)
Interest expense on debt	256	226	511	451
Other expenses	3,113	2,800	6,143	5,633
Total expenses	16,669	15,720	31,193	30,965
Provision for income tax expense (benefit)	441	512	793	988
Adjusted earnings	1,524	1,767	2,774	3,525
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	32	(921)	71	(1,629)
Other revenues	(7)	48	(10)	98
Net investment gains (losses)	(1,039)	(682)	(1,723)	(1,199)
Net derivative gains (losses)	(997)	(970)	(1,087)	(1,921)
Total revenues	(2,011)	(2,525)	(2,749)	(4,599)
Expenses
Policyholder benefits and claims and policyholder dividends	30	181	100	335
Policyholder liability remeasurement (gains) losses	0	0	0	0
Market risk benefit remeasurement (gains) losses	(817)	(757)	(629)	(2,197)
Interest credited to policyholder account balances	291	(726)	613	(1,291)
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	20	68	47	147
Total expenses	(476)	(1,234)	131	(3,009)
Provision for income tax expense (benefit)	(419)	(439)	(599)	(619)
U.S.
Expenses
Capitalization of DAC			(106)	(55)
U.S. | Operating Segments [Member]
Revenues
Premiums	8,108	8,094	14,060	15,099
Universal life and investment-type product policy fees	294	283	591	581
Net investment income	2,275	1,710	4,399	3,584
Other revenues	434	404	882	830
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	11,111	10,491	19,932	20,094
Expenses
Policyholder benefits and claims and policyholder dividends	8,307	8,115	14,526	15,532
Policyholder liability remeasurement (gains) losses	(9)	(7)	(42)	(30)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	750	453	1,442	859
Capitalization of DAC	(55)	(23)	(106)	(55)
Amortization of DAC and VOBA	19	15	36	32
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	5	1	8	3
Other expenses	1,096	949	2,174	1,928
Total expenses	10,113	9,503	18,038	18,269
Provision for income tax expense (benefit)	209	208	398	382
Adjusted earnings	789	780	1,496	1,443
Asia
Expenses
Capitalization of DAC			(798)	(769)
Asia | Operating Segments [Member]
Revenues
Premiums	1,310	1,393	2,687	2,945
Universal life and investment-type product policy fees	396	420	793	823
Net investment income	1,050	1,012	1,931	2,254
Other revenues	21	24	41	45
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,777	2,849	5,452	6,067
Expenses
Policyholder benefits and claims and policyholder dividends	1,057	1,123	2,187	2,394
Policyholder liability remeasurement (gains) losses	(27)	(10)	(16)	(34)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	570	493	1,106	991
Capitalization of DAC	(397)	(381)	(798)	(769)
Amortization of DAC and VOBA	190	182	383	376
Amortization of negative VOBA	(5)	(5)	(11)	(12)
Interest expense on debt	0	0	0	0
Other expenses	778	763	1,585	1,600
Total expenses	2,166	2,165	4,436	4,546
Provision for income tax expense (benefit)	180	198	305	436
Adjusted earnings	431	486	711	1,085
Latin America
Expenses
Capitalization of DAC			(299)	(227)
Latin America | Operating Segments [Member]
Revenues
Premiums	1,023	822	2,048	1,560
Universal life and investment-type product policy fees	352	294	687	583
Net investment income	418	459	797	781
Other revenues	10	10	22	19
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	1,803	1,585	3,554	2,943
Expenses
Policyholder benefits and claims and policyholder dividends	976	812	1,942	1,592
Policyholder liability remeasurement (gains) losses	3	6	(1)	(8)
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	105	84	204	152
Capitalization of DAC	(148)	(116)	(299)	(227)
Amortization of DAC and VOBA	117	101	223	201
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	4	4	6	7
Other expenses	465	364	895	713
Total expenses	1,522	1,255	2,970	2,430
Provision for income tax expense (benefit)	62	79	150	127
Adjusted earnings	219	251	434	386
EMEA
Expenses
Capitalization of DAC			(227)	(220)
EMEA | Operating Segments [Member]
Revenues
Premiums	499	493	995	1,002
Universal life and investment-type product policy fees	75	77	152	160
Net investment income	47	38	92	79
Other revenues	8	8	16	17
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	629	616	1,255	1,258
Expenses
Policyholder benefits and claims and policyholder dividends	237	226	498	502
Policyholder liability remeasurement (gains) losses	2	6	(1)	10
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	19	20	35	37
Capitalization of DAC	(119)	(108)	(227)	(209)
Amortization of DAC and VOBA	85	88	170	167
Amortization of negative VOBA	(1)	(2)	(2)	(3)
Interest expense on debt	0	0	0	0
Other expenses	314	298	614	594
Total expenses	537	528	1,087	1,098
Provision for income tax expense (benefit)	22	22	38	39
Adjusted earnings	70	66	130	121
MetLife Holdings
Expenses
Capitalization of DAC			(12)	(13)
MetLife Holdings | Operating Segments [Member]
Revenues
Premiums	719	760	1,442	1,536
Universal life and investment-type product policy fees	170	296	353	524
Net investment income	1,170	1,268	2,297	2,661
Other revenues	49	23	102	67
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,108	2,347	4,194	4,788
Expenses
Policyholder benefits and claims and policyholder dividends	1,341	1,354	2,710	2,836
Policyholder liability remeasurement (gains) losses	15	4	35	20
Market risk benefit remeasurement (gains) losses	0	0	0	0
Interest credited to policyholder account balances	198	203	397	405
Capitalization of DAC	(6)	(7)	(12)	(13)
Amortization of DAC and VOBA	64	70	132	145
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	3	2	6	3
Other expenses	231	242	469	478
Total expenses	1,846	1,868	3,737	3,874
Provision for income tax expense (benefit)	51	97	88	184
Adjusted earnings	211	382	369	730
Corporate & Other
Expenses
Capitalization of DAC			(5)	(5)
Corporate & Other | Operating Segments [Member]
Revenues
Premiums	19	(6)	35	(10)
Universal life and investment-type product policy fees	1	2	1	2
Net investment income	80	17	130	137
Other revenues	106	98	207	199
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	206	111	373	328
Expenses
Policyholder benefits and claims and policyholder dividends	12	(2)	28	(9)
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	(4)	(2)	(5)	(5)
Amortization of DAC and VOBA	4	2	5	4
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	244	219	491	438
Other expenses	229	184	406	320
Total expenses	485	401	925	748
Provision for income tax expense (benefit)	(83)	(92)	(186)	(180)
Adjusted earnings	$ (196)	$ (198)	$ (366)	$ (240)