Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Premiums	$ 10,876	$ 9,839	$ 29,421	$ 27,956
Universal life and investment-type product policy fees	1,428	1,341	4,152	4,127
Net investment income	4,295	4,609	12,909	12,527
Other revenues	301	356	935	1,309
Net investment gains (losses)	(606)	231	(439)	598
Net derivative gains (losses)	(190)	(543)	(663)	1,438
Total revenues	16,104	15,833	46,315	47,955
Expenses
Policyholder benefits and claims and policyholder dividends	10,947	9,914	29,848	28,318
Interest credited to policyholder account balances	1,338	1,544	4,081	3,819
Capitalization of DAC	(761)	(770)	(2,218)	(2,422)
Amortization of DAC and VOBA	626	660	1,945	2,052
Amortization of negative VOBA	(32)	(55)	(113)	(221)
Interest expense on debt	284	280	851	875
Other expenses	3,201	3,101	9,439	10,012
Total expenses	15,603	14,674	43,833	42,433
Provision for income tax expense (benefit)	(392)	135	(148)	1,253
Income from continuing operations, net of income tax	893	1,024	2,630	4,269
Operating Segments
Revenues
Premiums	10,913	10,045	29,768	28,054
Universal life and investment-type product policy fees	1,392	1,327	4,078	3,990
Net investment income	4,156	4,279	12,441	12,301
Other revenues	315	359	1,054	1,298
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	16,776	16,010	47,341	45,643
Expenses
Policyholder benefits and claims and policyholder dividends	10,717	10,079	29,642	28,374
Interest credited to policyholder account balances	1,105	1,026	3,207	3,062
Capitalization of DAC	(765)	(793)	(2,252)	(2,400)
Amortization of DAC and VOBA	553	772	1,905	2,355
Amortization of negative VOBA	(30)	(50)	(105)	(178)
Interest expense on debt	284	293	867	913
Other expenses	3,121	2,995	9,167	9,661
Total expenses	14,985	14,322	42,431	41,787
Provision for income tax expense (benefit)	617	327	1,257	815
Operating earnings	1,174	1,361	3,653	3,041
Operating Segments | U.S.
Revenues
Premiums	6,987	5,936	18,049	16,127
Universal life and investment-type product policy fees	247	245	763	743
Net investment income	1,602	1,590	4,789	4,615
Other revenues	197	192	600	589
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	9,033	7,963	24,201	22,074
Expenses
Policyholder benefits and claims and policyholder dividends	6,904	5,894	18,017	16,210
Interest credited to policyholder account balances	376	322	1,086	967
Capitalization of DAC	(126)	(124)	(342)	(356)
Amortization of DAC and VOBA	118	117	346	353
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	2	2	8	7
Other expenses	933	912	2,756	2,772
Total expenses	8,207	7,123	21,871	19,953
Provision for income tax expense (benefit)	280	288	782	720
Operating earnings	546	552	1,548	1,401
Operating Segments | Asia
Revenues
Premiums	1,696	1,822	5,063	5,161
Universal life and investment-type product policy fees	458	394	1,199	1,114
Net investment income	762	707	2,193	2,003
Other revenues	11	12	32	45
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,927	2,935	8,487	8,323
Expenses
Policyholder benefits and claims and policyholder dividends	1,223	1,363	3,785	3,923
Interest credited to policyholder account balances	349	331	1,003	974
Capitalization of DAC	(420)	(440)	(1,268)	(1,251)
Amortization of DAC and VOBA	424	331	1,005	921
Amortization of negative VOBA	(24)	(46)	(91)	(167)
Interest expense on debt	0	0	0	0
Other expenses	905	930	2,675	2,658
Total expenses	2,457	2,469	7,109	7,058
Provision for income tax expense (benefit)	156	142	459	377
Operating earnings	314	324	919	888
Operating Segments | Latin America
Revenues
Premiums	701	653	1,993	1,885
Universal life and investment-type product policy fees	229	227	764	764
Net investment income	299	311	891	809
Other revenues	7	11	24	26
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	1,236	1,202	3,672	3,484
Expenses
Policyholder benefits and claims and policyholder dividends	640	681	1,869	1,814
Interest credited to policyholder account balances	99	85	275	249
Capitalization of DAC	(94)	(83)	(264)	(236)
Amortization of DAC and VOBA	0	(2)	146	127
Amortization of negative VOBA	(1)	(1)	(1)	(1)
Interest expense on debt	1	1	4	1
Other expenses	377	335	1,060	968
Total expenses	1,022	1,016	3,089	2,922
Provision for income tax expense (benefit)	51	53	123	141
Operating earnings	163	133	460	421
Operating Segments | EMEA
Revenues
Premiums	527	500	1,534	1,519
Universal life and investment-type product policy fees	109	104	296	294
Net investment income	77	81	229	244
Other revenues	(2)	17	43	56
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	711	702	2,102	2,113
Expenses
Policyholder benefits and claims and policyholder dividends	282	257	821	801
Interest credited to policyholder account balances	26	28	75	87
Capitalization of DAC	(109)	(103)	(301)	(310)
Amortization of DAC and VOBA	78	106	260	311
Amortization of negative VOBA	(5)	(3)	(13)	(10)
Interest expense on debt	0	0	0	0
Other expenses	347	332	995	1,001
Total expenses	619	617	1,837	1,880
Provision for income tax expense (benefit)	21	11	47	32
Operating earnings	71	74	218	201
Operating Segments | MetLife Holdings
Revenues
Premiums	989	1,093	3,070	3,312
Universal life and investment-type product policy fees	349	357	1,056	1,073
Net investment income	1,390	1,537	4,232	4,489
Other revenues	37	105	170	512
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,765	3,092	8,528	9,386
Expenses
Policyholder benefits and claims and policyholder dividends	1,661	1,853	5,117	5,603
Interest credited to policyholder account balances	255	261	767	780
Capitalization of DAC	(14)	(44)	(71)	(240)
Amortization of DAC and VOBA	(70)	219	143	636
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	2	15	22	43
Other expenses	322	401	1,032	1,861
Total expenses	2,156	2,705	7,010	8,683
Provision for income tax expense (benefit)	199	121	488	203
Operating earnings	410	266	1,030	500
Operating Segments | Corporate & Other
Revenues
Premiums	13	41	59	50
Universal life and investment-type product policy fees	0	0	0	2
Net investment income	26	53	107	141
Other revenues	65	22	185	70
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	104	116	351	263
Expenses
Policyholder benefits and claims and policyholder dividends	7	31	33	23
Interest credited to policyholder account balances	0	(1)	1	5
Capitalization of DAC	(2)	1	(6)	(7)
Amortization of DAC and VOBA	3	1	5	7
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	279	275	833	862
Other expenses	237	85	649	401
Total expenses	524	392	1,515	1,291
Provision for income tax expense (benefit)	(90)	(288)	(642)	(658)
Operating earnings	(330)	12	(522)	(370)
Significant Reconciling Items
Revenues
Premiums	(37)	(206)	(347)	(98)
Universal life and investment-type product policy fees	36	14	74	137
Net investment income	139	330	468	226
Other revenues	(14)	(3)	(119)	11
Net investment gains (losses)	(606)	231	(439)	598
Net derivative gains (losses)	(190)	(543)	(663)	1,438
Total revenues	(672)	(177)	(1,026)	2,312
Expenses
Policyholder benefits and claims and policyholder dividends	230	(165)	206	(56)
Interest credited to policyholder account balances	233	518	874	757
Capitalization of DAC	4	23	34	(22)
Amortization of DAC and VOBA	73	(112)	40	(303)
Amortization of negative VOBA	(2)	(5)	(8)	(43)
Interest expense on debt	0	(13)	(16)	(38)
Other expenses	80	106	272	351
Total expenses	618	352	1,402	646
Provision for income tax expense (benefit)	$ (1,009)	$ (192)	$ (1,405)	$ 438