Consolidated Supplementary Insurance Information (Balance Sheet Items) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	$ 18,419	$ 17,590	$ 17,430
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	195,610	181,969	176,208
Policyholder account balances	182,518	172,486	165,130
Policyholder Dividends Payable	682	696	709
Unearned Premiums	4,592	4,724	4,401
Unearned Revenue	2,274	2,059	2,135
U.S.
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	614	616	615
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	65,610	61,578	59,413
Policyholder account balances	70,455	67,539	63,986
Policyholder Dividends Payable	0	0	0
Unearned Premiums	1,907	1,843	1,820
Unearned Revenue	24	30	33
Asia
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	9,261	8,707	8,386
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	39,702	36,308	34,397
Policyholder account balances	59,702	53,114	49,094
Policyholder Dividends Payable	80	95	88
Unearned Premiums	2,378	2,167	1,859
Unearned Revenue	916	912	974
Latin America
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	2,050	1,808	1,753
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	10,397	9,163	8,142
Policyholder account balances	6,361	5,597	5,880
Policyholder Dividends Payable	0	0	0
Unearned Premiums	115	448	491
Unearned Revenue	675	563	597
EMEA
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	1,673	1,472	1,532
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	5,768	5,439	5,837
Policyholder account balances	13,811	12,636	13,172
Policyholder Dividends Payable	7	6	7
Unearned Premiums	24	64	60
Unearned Revenue	454	372	336
MetLife Holdings
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	4,797	5,246	5,436
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	73,317	72,220	70,764
Policyholder account balances	32,176	33,982	33,320
Policyholder Dividends Payable	595	604	621
Unearned Premiums	167	204	171
Unearned Revenue	205	209	218
Corporate & Other
Supplementary Insurance Information, by Segment [Line Items]
DAC and VOBA	24	(259)	(292)
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	816	(2,739)	(2,345)
Policyholder account balances	13	(382)	(322)
Policyholder Dividends Payable	0	(9)	(7)
Unearned Premiums	1	(2)	0
Unearned Revenue	$ 0	$ (27)	$ (23)