Consolidated Supplementary Insurance Information (Income Statement Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	$ 47,838	$ 49,342	$ 44,502
Net Investment Income	18,868	16,166	17,363
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	47,925	46,669	43,920
Amortization of DAC and VOBA Charged to Other Expenses	2,896	2,975	2,681
Other Expenses (1)	12,004	11,990	12,171
U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	27,879	29,239	24,644
Net Investment Income	6,821	6,703	6,201
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	28,165	29,539	25,103
Amortization of DAC and VOBA Charged to Other Expenses	475	477	459
Other Expenses (1)	3,603	3,466	3,235
Asia
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	8,482	8,390	8,352
Net Investment Income	3,920	3,055	3,299
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	7,278	6,559	6,799
Amortization of DAC and VOBA Charged to Other Expenses	1,380	1,297	1,310
Other Expenses (1)	1,907	1,903	1,802
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	3,817	3,737
Net Investment Income	1,262	1,194	1,288
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	3,210	3,057	2,973
Amortization of DAC and VOBA Charged to Other Expenses	291	209	224
Other Expenses (1)	1,039	1,044	1,111
EMEA
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	2,615	2,587	2,492
Net Investment Income	1,442	(195)	1,157
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	2,361	772	2,012
Amortization of DAC and VOBA Charged to Other Expenses	420	433	356
Other Expenses (1)	921	909	966
MetLife Holdings
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	4,960	5,191	5,603
Net Investment Income	5,140	5,222	5,426
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	6,842	6,662	7,097
Amortization of DAC and VOBA Charged to Other Expenses	324	553	234
Other Expenses (1)	2,246	2,286	2,550
Corporate & Other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	85	118	(326)
Net Investment Income	283	187	(8)
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	69	80	(64)
Amortization of DAC and VOBA Charged to Other Expenses	6	6	98
Other Expenses (1)	$ 2,288	$ 2,382	$ 2,507