Consolidated Supplementary Insurance Information (Income Statement Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	$ 49,342	$ 44,502	$ 42,685
Net Investment Income	16,166	17,363	16,790
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	46,669	43,920	41,534
Amortization of DAC and VOBA Charged to Other Expenses	2,975	2,681	2,718
Other Expenses (1)	11,990	12,171	12,254
U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	29,239	24,644	22,490
Net Investment Income	6,703	6,201	5,942
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	29,539	25,103	22,892
Amortization of DAC and VOBA Charged to Other Expenses	477	459	471
Other Expenses (1)	3,466	3,235	3,244
Asia
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	8,390	8,352	8,914
Net Investment Income	3,055	3,299	2,807
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	6,559	6,799	6,916
Amortization of DAC and VOBA Charged to Other Expenses	1,297	1,310	1,350
Other Expenses (1)	1,903	1,802	1,795
Latin America
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	3,817	3,737	3,554
Net Investment Income	1,194	1,288	1,133
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	3,057	2,973	2,770
Amortization of DAC and VOBA Charged to Other Expenses	209	224	184
Other Expenses (1)	1,044	1,111	1,007
EMEA
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	2,587	2,492	2,442
Net Investment Income	(195)	1,157	1,229
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	772	2,012	2,064
Amortization of DAC and VOBA Charged to Other Expenses	433	356	408
Other Expenses (1)	909	966	924
MetLife Holdings
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	5,191	5,603	6,034
Net Investment Income	5,222	5,426	5,670
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	6,662	7,097	7,521
Amortization of DAC and VOBA Charged to Other Expenses	553	234	424
Other Expenses (1)	2,286	2,550	3,392
Corporate & Other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	118	(326)	(749)
Net Investment Income	187	(8)	9
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	80	(64)	(629)
Amortization of DAC and VOBA Charged to Other Expenses	6	98	(119)
Other Expenses (1)	$ 2,382	$ 2,507	$ 1,892