Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Revenues
Premiums	$ 10,781	$ 10,242	$ 30,315	$ 34,573
Universal life and investment-type product policy fees	1,440	1,343	4,217	4,105
Net investment income	4,623	4,486	14,224	12,704
Other revenues	419	479	1,391	1,428
Net investment gains (losses)	161	117	237	(443)
Net derivative gains (losses)	1,254	(378)	2,093	(88)
Total revenues	18,678	16,289	52,477	52,279
Expenses
Policyholder benefits and claims and policyholder dividends	10,944	10,407	30,611	34,597
Interest credited to policyholder account balances	1,500	1,334	4,976	3,527
Capitalization of DAC	(882)	(810)	(2,531)	(2,440)
Amortization of DAC and VOBA	797	732	2,110	2,132
Amortization of negative VOBA	(4)	(7)	(24)	(45)
Interest expense on debt	223	267	731	862
Other expenses	3,309	3,287	9,772	9,810
Total expenses	15,887	15,210	45,645	48,443
Provision for income tax expense (benefit)	601	164	1,511	770
Income (loss) from continuing operations, net of income tax	2,190	915	5,321	3,066
Operating Segments
Revenues
Premiums	10,746	10,242	30,280	34,573
Universal life and investment-type product policy fees	1,352	1,300	4,054	4,004
Net investment income	4,473	4,462	13,308	13,008
Other revenues	347	396	1,178	1,179
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	16,918	16,400	48,820	52,764
Expenses
Policyholder benefits and claims and policyholder dividends	10,858	10,252	30,282	34,345
Interest credited to policyholder account balances	1,274	1,202	3,786	3,476
Capitalization of DAC	(871)	(810)	(2,520)	(2,439)
Amortization of DAC and VOBA	756	624	2,108	2,029
Amortization of negative VOBA	(4)	(7)	(24)	(44)
Interest expense on debt	223	252	731	817
Other expenses	3,199	3,187	9,492	9,474
Total expenses	15,435	14,700	43,855	47,658
Provision for income tax expense (benefit)	261	292	911	897
Adjusted earnings	1,222	1,408	4,054	4,209
Operating Segments | U.S.
Revenues
Premiums	6,903	6,431	18,704	22,950
Universal life and investment-type product policy fees	264	252	808	772
Net investment income	1,760	1,787	5,274	5,168
Other revenues	224	206	668	613
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	9,151	8,676	25,454	29,503
Expenses
Policyholder benefits and claims and policyholder dividends	6,759	6,219	18,233	22,590
Interest credited to policyholder account balances	507	457	1,512	1,303
Capitalization of DAC	(131)	(116)	(372)	(336)
Amortization of DAC and VOBA	121	128	352	357
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	3	2	8	8
Other expenses	1,004	982	3,006	2,908
Total expenses	8,263	7,672	22,739	26,830
Provision for income tax expense (benefit)	181	209	552	554
Adjusted earnings	707	795	2,163	2,119
Operating Segments | Asia
Revenues
Premiums	1,654	1,689	4,984	5,091
Universal life and investment-type product policy fees	430	428	1,255	1,221
Net investment income	915	830	2,739	2,464
Other revenues	14	12	43	40
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	3,013	2,959	9,021	8,816
Expenses
Policyholder benefits and claims and policyholder dividends	1,264	1,354	3,862	3,934
Interest credited to policyholder account balances	440	381	1,267	1,094
Capitalization of DAC	(498)	(478)	(1,449)	(1,438)
Amortization of DAC and VOBA	353	366	972	993
Amortization of negative VOBA	(2)	(4)	(18)	(31)
Interest expense on debt	0	0	0	0
Other expenses	955	943	2,865	2,871
Total expenses	2,512	2,562	7,499	7,423
Provision for income tax expense (benefit)	152	131	458	437
Adjusted earnings	349	266	1,064	956
Operating Segments | Latin America
Revenues
Premiums	703	692	2,122	2,079
Universal life and investment-type product policy fees	256	229	820	786
Net investment income	295	339	951	942
Other revenues	8	7	31	24
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	1,262	1,267	3,924	3,831
Expenses
Policyholder benefits and claims and policyholder dividends	656	670	2,043	1,976
Interest credited to policyholder account balances	74	102	254	295
Capitalization of DAC	(102)	(97)	(296)	(282)
Amortization of DAC and VOBA	58	5	215	136
Amortization of negative VOBA	0	(1)	0	(1)
Interest expense on debt	0	2	2	5
Other expenses	356	351	1,074	1,052
Total expenses	1,042	1,032	3,292	3,181
Provision for income tax expense (benefit)	65	65	184	195
Adjusted earnings	155	170	448	455
Operating Segments | EMEA
Revenues
Premiums	526	514	1,619	1,611
Universal life and investment-type product policy fees	117	105	325	324
Net investment income	73	73	220	221
Other revenues	13	15	40	51
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	729	707	2,204	2,207
Expenses
Policyholder benefits and claims and policyholder dividends	291	281	867	861
Interest credited to policyholder account balances	25	24	72	75
Capitalization of DAC	(128)	(109)	(371)	(348)
Amortization of DAC and VOBA	128	110	327	324
Amortization of negative VOBA	(2)	(2)	(6)	(12)
Interest expense on debt	0	0	0	0
Other expenses	341	333	1,029	1,023
Total expenses	655	637	1,918	1,923
Provision for income tax expense (benefit)	21	15	70	62
Adjusted earnings	53	55	216	222
Operating Segments | MetLife Holdings
Revenues
Premiums	925	949	2,776	2,856
Universal life and investment-type product policy fees	284	286	844	901
Net investment income	1,316	1,375	3,941	4,056
Other revenues	52	70	184	205
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,577	2,680	7,745	8,018
Expenses
Policyholder benefits and claims and policyholder dividends	1,856	1,766	5,207	5,022
Interest credited to policyholder account balances	228	238	681	709
Capitalization of DAC	(9)	(8)	(23)	(28)
Amortization of DAC and VOBA	94	13	237	214
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	2	2	6	6
Other expenses	223	264	687	815
Total expenses	2,394	2,275	6,795	6,738
Provision for income tax expense (benefit)	34	78	185	248
Adjusted earnings	149	327	765	1,032
Operating Segments | Corporate & Other
Revenues
Premiums	35	(33)	75	(14)
Universal life and investment-type product policy fees	1	0	2	0
Net investment income	114	58	183	157
Other revenues	36	86	212	246
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	186	111	472	389
Expenses
Policyholder benefits and claims and policyholder dividends	32	(38)	70	(38)
Interest credited to policyholder account balances	0	0	0	0
Capitalization of DAC	(3)	(2)	(9)	(7)
Amortization of DAC and VOBA	2	2	5	5
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	218	246	715	798
Other expenses	320	314	831	805
Total expenses	569	522	1,612	1,563
Provision for income tax expense (benefit)	(192)	(206)	(538)	(599)
Adjusted earnings	(191)	(205)	(602)	(575)
Significant Reconciling Items
Revenues
Premiums	35	0	35	0
Universal life and investment-type product policy fees	88	43	163	101
Net investment income	150	24	916	(304)
Other revenues	72	83	213	249
Net investment gains (losses)	161	117	237	(443)
Net derivative gains (losses)	1,254	(378)	2,093	(88)
Total revenues	1,760	(111)	3,657	(485)
Expenses
Policyholder benefits and claims and policyholder dividends	86	155	329	252
Interest credited to policyholder account balances	226	132	1,190	51
Capitalization of DAC	(11)	0	(11)	(1)
Amortization of DAC and VOBA	41	108	2	103
Amortization of negative VOBA	0	0	0	(1)
Interest expense on debt	0	15	0	45
Other expenses	110	100	280	336
Total expenses	452	510	1,790	785
Provision for income tax expense (benefit)	$ 340	$ (128)	$ 600	$ (127)