Segment Information (Earnings) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues
Premiums	$ 9,466	$ 9,405
Universal life and investment-type product policy fees	1,431	1,365
Net investment income	3,061	4,908
Other revenues	439	494
Net investment gains (losses)	(288)	15
Net derivative gains (losses)	4,201	115
Total revenues	18,310	16,302
Expenses
Policyholder benefits and claims and policyholder dividends	9,314	9,372
Interest credited to policyholder account balances	80	1,961
Capitalization of DAC	(774)	(812)
Amortization of DAC and VOBA	788	624
Amortization of negative VOBA	(10)	(10)
Interest expense on debt	222	234
Other expenses	3,047	3,189
Total expenses	12,667	14,558
Provision for income tax expense (benefit)	1,242	359
Income (loss) from continuing operations, net of income tax	4,401	1,385
Operating Segments
Revenues
Premiums	9,434	9,405
Universal life and investment-type product policy fees	1,385	1,338
Net investment income	4,321	4,281
Other revenues	397	424
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	15,537	15,448
Expenses
Policyholder benefits and claims and policyholder dividends	9,363	9,241
Interest credited to policyholder account balances	1,218	1,248
Capitalization of DAC	(771)	(812)
Amortization of DAC and VOBA	739	655
Amortization of negative VOBA	(10)	(10)
Interest expense on debt	222	234
Other expenses	2,981	3,101
Total expenses	13,742	13,657
Provision for income tax expense (benefit)	314	335
Adjusted earnings	1,481	1,456
Operating Segments | U.S.
Revenues
Premiums	5,674	5,567
Universal life and investment-type product policy fees	275	270
Net investment income	1,766	1,719
Other revenues	240	221
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	7,955	7,777
Expenses
Policyholder benefits and claims and policyholder dividends	5,435	5,373
Interest credited to policyholder account balances	458	501
Capitalization of DAC	(112)	(114)
Amortization of DAC and VOBA	119	114
Amortization of negative VOBA	0	0
Interest expense on debt	2	2
Other expenses	1,066	993
Total expenses	6,968	6,869
Provision for income tax expense (benefit)	207	184
Adjusted earnings	780	724
Operating Segments | Asia
Revenues
Premiums	1,636	1,699
Universal life and investment-type product policy fees	430	406
Net investment income	937	880
Other revenues	14	16
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	3,017	3,001
Expenses
Policyholder benefits and claims and policyholder dividends	1,321	1,319
Interest credited to policyholder account balances	445	403
Capitalization of DAC	(421)	(479)
Amortization of DAC and VOBA	315	307
Amortization of negative VOBA	(8)	(9)
Interest expense on debt	0	0
Other expenses	874	955
Total expenses	2,526	2,496
Provision for income tax expense (benefit)	141	149
Adjusted earnings	350	356
Operating Segments | Latin America
Revenues
Premiums	640	646
Universal life and investment-type product policy fees	270	284
Net investment income	218	296
Other revenues	11	12
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	1,139	1,238
Expenses
Policyholder benefits and claims and policyholder dividends	610	597
Interest credited to policyholder account balances	70	94
Capitalization of DAC	(100)	(94)
Amortization of DAC and VOBA	74	78
Amortization of negative VOBA	0	0
Interest expense on debt	1	1
Other expenses	345	366
Total expenses	1,000	1,042
Provision for income tax expense (benefit)	44	62
Adjusted earnings	95	134
Operating Segments | EMEA
Revenues
Premiums	568	542
Universal life and investment-type product policy fees	116	103
Net investment income	69	74
Other revenues	13	14
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	766	733
Expenses
Policyholder benefits and claims and policyholder dividends	310	284
Interest credited to policyholder account balances	27	24
Capitalization of DAC	(130)	(117)
Amortization of DAC and VOBA	130	92
Amortization of negative VOBA	(2)	(1)
Interest expense on debt	0	0
Other expenses	332	338
Total expenses	667	620
Provision for income tax expense (benefit)	21	27
Adjusted earnings	78	86
Operating Segments | MetLife Holdings
Revenues
Premiums	904	927
Universal life and investment-type product policy fees	294	274
Net investment income	1,315	1,287
Other revenues	35	67
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	2,548	2,555
Expenses
Policyholder benefits and claims and policyholder dividends	1,661	1,648
Interest credited to policyholder account balances	218	226
Capitalization of DAC	(5)	(6)
Amortization of DAC and VOBA	100	63
Amortization of negative VOBA	0	0
Interest expense on debt	2	2
Other expenses	228	227
Total expenses	2,204	2,160
Provision for income tax expense (benefit)	67	78
Adjusted earnings	277	317
Operating Segments | Corporate & Other
Revenues
Premiums	12	24
Universal life and investment-type product policy fees	0	1
Net investment income	16	25
Other revenues	84	94
Net investment gains (losses)	0	0
Net derivative gains (losses)	0	0
Total revenues	112	144
Expenses
Policyholder benefits and claims and policyholder dividends	26	20
Interest credited to policyholder account balances	0	0
Capitalization of DAC	(3)	(2)
Amortization of DAC and VOBA	1	1
Amortization of negative VOBA	0	0
Interest expense on debt	217	229
Other expenses	136	222
Total expenses	377	470
Provision for income tax expense (benefit)	(166)	(165)
Adjusted earnings	(99)	(161)
Significant Reconciling Items
Revenues
Premiums	32	0
Universal life and investment-type product policy fees	46	27
Net investment income	(1,260)	627
Other revenues	42	70
Net investment gains (losses)	(288)	15
Net derivative gains (losses)	4,201	115
Total revenues	2,773	854
Expenses
Policyholder benefits and claims and policyholder dividends	(49)	131
Interest credited to policyholder account balances	(1,138)	713
Capitalization of DAC	(3)	0
Amortization of DAC and VOBA	49	(31)
Amortization of negative VOBA	0	0
Interest expense on debt	0	0
Other expenses	66	88
Total expenses	(1,075)	901
Provision for income tax expense (benefit)	$ 928	$ 24