Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues
Premiums	$ 9,178	$ 8,965
Universal life and investment-type product policy fees	1,392	1,360
Net investment income	3,745	4,421
Other revenues	474	342
Net investment gains (losses)	(333)	88
Net derivative gains (losses)	349	(212)
Total revenues	14,805	14,964
Expenses
Policyholder benefits and claims and policyholder dividends	9,015	9,173
Interest credited to policyholder account balances	769	1,451
Capitalization of DAC	(796)	(713)
Amortization of DAC and VOBA	693	663
Amortization of negative VOBA	(22)	(43)
Interest expense on debt	286	283
Other expenses	3,204	3,078
Total expenses	13,149	13,892
Provision for income tax expense (benefit)	399	120
Income (loss) from continuing operations, net of income tax	1,257	952
Operating Segments
Revenues
Premiums	9,178	9,139
Universal life and investment-type product policy fees	1,360	1,348
Net investment income	4,219	4,172
Other revenues	391	395
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	15,148	15,054
Expenses
Policyholder benefits and claims and policyholder dividends	8,968	9,219
Interest credited to policyholder account balances	1,117	1,036
Capitalization of DAC	(795)	(729)
Amortization of DAC and VOBA	697	645
Amortization of negative VOBA	(21)	(40)
Interest expense on debt	286	295
Other expenses	3,110	2,941
Total expenses	13,362	13,367
Provision for income tax expense (benefit)	357	360
Adjusted earnings	1,429	1,327
Operating Segments | U.S.
Revenues
Premiums	5,217	5,185
Universal life and investment-type product policy fees	258	265
Net investment income	1,662	1,612
Other revenues	204	204
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	7,341	7,266
Expenses
Policyholder benefits and claims and policyholder dividends	5,138	5,244
Interest credited to policyholder account balances	407	351
Capitalization of DAC	(106)	(100)
Amortization of DAC and VOBA	115	114
Amortization of negative VOBA	0	0
Interest expense on debt	2	2
Other expenses	961	909
Total expenses	6,517	6,520
Provision for income tax expense (benefit)	171	249
Adjusted earnings	653	497
Operating Segments | Asia
Revenues
Premiums	1,748	1,708
Universal life and investment-type product policy fees	394	366
Net investment income	795	702
Other revenues	15	10
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	2,952	2,786
Expenses
Policyholder benefits and claims and policyholder dividends	1,343	1,315
Interest credited to policyholder account balances	351	321
Capitalization of DAC	(465)	(420)
Amortization of DAC and VOBA	314	291
Amortization of negative VOBA	(15)	(37)
Interest expense on debt	0	0
Other expenses	952	875
Total expenses	2,480	2,345
Provision for income tax expense (benefit)	145	146
Adjusted earnings	327	295
Operating Segments | Latin America
Revenues
Premiums	699	647
Universal life and investment-type product policy fees	282	260
Net investment income	276	303
Other revenues	8	9
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	1,265	1,219
Expenses
Policyholder benefits and claims and policyholder dividends	646	633
Interest credited to policyholder account balances	98	82
Capitalization of DAC	(94)	(82)
Amortization of DAC and VOBA	60	78
Amortization of negative VOBA	0	0
Interest expense on debt	2	1
Other expenses	338	326
Total expenses	1,050	1,038
Provision for income tax expense (benefit)	75	38
Adjusted earnings	140	143
Operating Segments | EMEA
Revenues
Premiums	551	502
Universal life and investment-type product policy fees	112	95
Net investment income	75	74
Other revenues	16	17
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	754	688
Expenses
Policyholder benefits and claims and policyholder dividends	294	269
Interest credited to policyholder account balances	25	24
Capitalization of DAC	(118)	(92)
Amortization of DAC and VOBA	106	87
Amortization of negative VOBA	(6)	(3)
Interest expense on debt	0	0
Other expenses	351	316
Total expenses	652	601
Provision for income tax expense (benefit)	21	12
Adjusted earnings	81	75
Operating Segments | MetLife Holdings
Revenues
Premiums	950	1,059
Universal life and investment-type product policy fees	314	362
Net investment income	1,352	1,441
Other revenues	67	96
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	2,683	2,958
Expenses
Policyholder benefits and claims and policyholder dividends	1,550	1,733
Interest credited to policyholder account balances	236	257
Capitalization of DAC	(10)	(34)
Amortization of DAC and VOBA	100	74
Amortization of negative VOBA	0	0
Interest expense on debt	2	15
Other expenses	276	340
Total expenses	2,154	2,385
Provision for income tax expense (benefit)	104	186
Adjusted earnings	425	387
Operating Segments | Corporate & Other
Revenues
Premiums	13	38
Universal life and investment-type product policy fees	0	0
Net investment income	59	40
Other revenues	81	59
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	153	137
Expenses
Policyholder benefits and claims and policyholder dividends	(3)	25
Interest credited to policyholder account balances	0	1
Capitalization of DAC	(2)	(1)
Amortization of DAC and VOBA	2	1
Amortization of negative VOBA	0	0
Interest expense on debt	280	277
Other expenses	232	175
Total expenses	509	478
Provision for income tax expense (benefit)	(159)	(271)
Adjusted earnings	(197)	(70)
Significant Reconciling Items
Revenues
Premiums	0	(174)
Universal life and investment-type product policy fees	32	12
Net investment income	(474)	249
Other revenues	83	(53)
Net investment gains (losses)	(333)	88
Net derivative gains (losses)	349	(212)
Total revenues	(343)	(90)
Expenses
Policyholder benefits and claims and policyholder dividends	47	(46)
Interest credited to policyholder account balances	(348)	415
Capitalization of DAC	(1)	16
Amortization of DAC and VOBA	(4)	18
Amortization of negative VOBA	(1)	(3)
Interest expense on debt	0	(12)
Other expenses	94	137
Total expenses	(213)	525
Provision for income tax expense (benefit)	$ 42	$ (240)