Consolidated Supplementary Insurance Information (Income Statement Items) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	$ 47,765	$ 47,637	$ 47,838
Net Investment Income	21,395	17,117	18,868
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	49,492	46,675	47,925
Amortization of DAC and VOBA Charged to Other Expenses	2,555	3,160	2,896
Other Expenses (1)	10,907	11,080	12,004
U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	28,363	28,335	27,879
Net Investment Income	7,738	6,563	6,821
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	29,987	27,966	28,165
Amortization of DAC and VOBA Charged to Other Expenses	158	471	475
Other Expenses (1)	3,707	3,716	3,603
Asia
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	8,308	8,554	8,482
Net Investment Income	5,110	3,931	3,920
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	7,295	7,249	7,278
Amortization of DAC and VOBA Charged to Other Expenses	1,404	1,468	1,380
Other Expenses (1)	1,751	1,825	1,907
Latin America
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	3,718	3,257	3,817
Net Investment Income	1,207	991	1,262
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	3,442	2,857	3,210
Amortization of DAC and VOBA Charged to Other Expenses	285	276	291
Other Expenses (1)	989	971	1,039
EMEA
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	2,825	2,709	2,615
Net Investment Income	932	697	1,442
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	2,162	1,623	2,361
Amortization of DAC and VOBA Charged to Other Expenses	382	452	420
Other Expenses (1)	900	860	921
MetLife Holdings
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	4,514	4,757	4,960
Net Investment Income	6,157	4,900	5,140
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	6,571	6,983	6,842
Amortization of DAC and VOBA Charged to Other Expenses	317	485	324
Other Expenses (1)	1,839	1,976	2,246
Corporate & Other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
Premiums and Universal Life and Investment-Type Product Policy Fees	37	25	85
Net Investment Income	251	35	283
Policyholder Benefits and Claims and Interest Credited to Policyholder Account Balances	35	(3)	69
Amortization of DAC and VOBA Charged to Other Expenses	9	8	6
Other Expenses (1)	$ 1,721	$ 1,732	$ 2,288