Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues
Premiums	$ 10,129	$ 15,153	$ 19,534	$ 24,331
Universal life and investment-type product policy fees	1,412	1,370	2,777	2,762
Net investment income	4,693	4,473	9,601	8,218
Other revenues	478	475	972	949
Net investment gains (losses)	61	(227)	76	(560)
Net derivative gains (losses)	724	(59)	839	290
Total revenues	17,497	21,185	33,799	35,990
Expenses
Policyholder benefits and claims and policyholder dividends	10,295	15,175	19,667	24,190
Interest credited to policyholder account balances	1,515	1,424	3,476	2,193
Capitalization of DAC	(837)	(834)	(1,649)	(1,630)
Amortization of DAC and VOBA	689	707	1,313	1,400
Amortization of negative VOBA	(10)	(16)	(20)	(38)
Interest expense on debt	274	309	508	595
Other expenses	3,274	3,319	6,463	6,523
Total expenses	15,200	20,084	29,758	33,233
Provision for income tax expense (benefit)	551	207	910	606
Income (loss) from continuing operations, net of income tax	1,746	894	3,131	2,151
Operating Segments
Revenues
Premiums	10,129	15,153	19,534	24,331
Universal life and investment-type product policy fees	1,364	1,344	2,702	2,704
Net investment income	4,554	4,327	8,835	8,546
Other revenues	407	392	831	783
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	16,454	21,216	31,902	36,364
Expenses
Policyholder benefits and claims and policyholder dividends	10,183	15,125	19,424	24,093
Interest credited to policyholder account balances	1,264	1,157	2,512	2,274
Capitalization of DAC	(837)	(834)	(1,649)	(1,629)
Amortization of DAC and VOBA	697	708	1,352	1,405
Amortization of negative VOBA	(10)	(16)	(20)	(37)
Interest expense on debt	274	279	508	565
Other expenses	3,192	3,177	6,293	6,287
Total expenses	14,763	19,596	28,420	32,958
Provision for income tax expense (benefit)	315	248	650	605
Adjusted earnings	1,376	1,372	2,832	2,801
Operating Segments | U.S.
Revenues
Premiums	6,234	11,302	11,801	16,519
Universal life and investment-type product policy fees	274	262	544	520
Net investment income	1,795	1,719	3,514	3,381
Other revenues	223	203	444	407
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	8,526	13,486	16,303	20,827
Expenses
Policyholder benefits and claims and policyholder dividends	6,101	11,233	11,474	16,371
Interest credited to policyholder account balances	504	439	1,005	846
Capitalization of DAC	(127)	(114)	(241)	(220)
Amortization of DAC and VOBA	117	114	231	229
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	3	4	5	6
Other expenses	1,009	965	2,002	1,926
Total expenses	7,607	12,641	14,476	19,158
Provision for income tax expense (benefit)	187	174	371	345
Adjusted earnings	732	671	1,456	1,324
Operating Segments | Asia
Revenues
Premiums	1,631	1,654	3,330	3,402
Universal life and investment-type product policy fees	419	399	825	793
Net investment income	944	839	1,824	1,634
Other revenues	13	13	29	28
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	3,007	2,905	6,008	5,857
Expenses
Policyholder benefits and claims and policyholder dividends	1,279	1,237	2,598	2,580
Interest credited to policyholder account balances	424	362	827	713
Capitalization of DAC	(472)	(495)	(951)	(960)
Amortization of DAC and VOBA	312	313	619	627
Amortization of negative VOBA	(7)	(12)	(16)	(27)
Interest expense on debt	0	0	0	0
Other expenses	955	976	1,910	1,928
Total expenses	2,491	2,381	4,987	4,861
Provision for income tax expense (benefit)	157	161	306	306
Adjusted earnings	359	363	715	690
Operating Segments | Latin America
Revenues
Premiums	773	688	1,419	1,387
Universal life and investment-type product policy fees	280	275	564	557
Net investment income	360	327	656	603
Other revenues	11	9	23	17
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	1,424	1,299	2,662	2,564
Expenses
Policyholder benefits and claims and policyholder dividends	790	660	1,387	1,306
Interest credited to policyholder account balances	86	95	180	193
Capitalization of DAC	(100)	(91)	(194)	(185)
Amortization of DAC and VOBA	79	71	157	131
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	1	1	2	3
Other expenses	352	363	718	701
Total expenses	1,208	1,099	2,250	2,149
Provision for income tax expense (benefit)	57	55	119	130
Adjusted earnings	159	145	293	285
Operating Segments | EMEA
Revenues
Premiums	551	546	1,093	1,097
Universal life and investment-type product policy fees	105	107	208	219
Net investment income	73	73	147	148
Other revenues	13	20	27	36
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	742	746	1,475	1,500
Expenses
Policyholder benefits and claims and policyholder dividends	292	286	576	580
Interest credited to policyholder account balances	23	26	47	51
Capitalization of DAC	(126)	(121)	(243)	(239)
Amortization of DAC and VOBA	107	108	199	214
Amortization of negative VOBA	(3)	(4)	(4)	(10)
Interest expense on debt	0	0	0	0
Other expenses	350	339	688	690
Total expenses	643	634	1,263	1,286
Provision for income tax expense (benefit)	22	26	49	47
Adjusted earnings	77	86	163	167
Operating Segments | MetLife Holdings
Revenues
Premiums	924	957	1,851	1,907
Universal life and investment-type product policy fees	286	301	560	615
Net investment income	1,338	1,329	2,625	2,681
Other revenues	65	68	132	135
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	2,613	2,655	5,168	5,338
Expenses
Policyholder benefits and claims and policyholder dividends	1,703	1,706	3,351	3,256
Interest credited to policyholder account balances	227	235	453	471
Capitalization of DAC	(8)	(10)	(14)	(20)
Amortization of DAC and VOBA	80	101	143	201
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	2	2	4	4
Other expenses	237	275	464	551
Total expenses	2,241	2,309	4,401	4,463
Provision for income tax expense (benefit)	73	66	151	170
Adjusted earnings	299	280	616	705
Operating Segments | Corporate & Other
Revenues
Premiums	16	6	40	19
Universal life and investment-type product policy fees	0	0	1	0
Net investment income	44	40	69	99
Other revenues	82	79	176	160
Net investment gains (losses)	0	0	0	0
Net derivative gains (losses)	0	0	0	0
Total revenues	142	125	286	278
Expenses
Policyholder benefits and claims and policyholder dividends	18	3	38	0
Interest credited to policyholder account balances	0	0	0	0
Capitalization of DAC	(4)	(3)	(6)	(5)
Amortization of DAC and VOBA	2	1	3	3
Amortization of negative VOBA	0	0	0	0
Interest expense on debt	268	272	497	552
Other expenses	289	259	511	491
Total expenses	573	532	1,043	1,041
Provision for income tax expense (benefit)	(181)	(234)	(346)	(393)
Adjusted earnings	(250)	(173)	(411)	(370)
Significant Reconciling Items
Revenues
Premiums	0	0	0	0
Universal life and investment-type product policy fees	48	26	75	58
Net investment income	139	146	766	(328)
Other revenues	71	83	141	166
Net investment gains (losses)	61	(227)	76	(560)
Net derivative gains (losses)	724	(59)	839	290
Total revenues	1,043	(31)	1,897	(374)
Expenses
Policyholder benefits and claims and policyholder dividends	112	50	243	97
Interest credited to policyholder account balances	251	267	964	(81)
Capitalization of DAC	0	0	0	(1)
Amortization of DAC and VOBA	(8)	(1)	(39)	(5)
Amortization of negative VOBA	0	0	0	(1)
Interest expense on debt	0	30	0	30
Other expenses	82	142	170	236
Total expenses	437	488	1,338	275
Provision for income tax expense (benefit)	$ 236	$ (41)	$ 260	$ 1