Consolidated Supplementary Insurance Information (Balance Sheet Items) (Details) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	$ 16,389	$ 17,833	$ 18,895
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	226,726	214,100
Policyholder account balances	205,176	192,627
Policyholder Dividends Payable	587	681
Unearned Premiums	2,846	4,647
Unearned Revenue	2,112	2,478
U.S.
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	434	649
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	85,037	79,147
Policyholder account balances	77,487	71,180
Policyholder Dividends Payable	0	0
Unearned Premiums	175	2,062
Unearned Revenue	42	41
Asia
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	9,333	9,764
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	45,202	42,328
Policyholder account balances	81,710	75,699
Policyholder Dividends Payable	87	75
Unearned Premiums	2,493	2,275
Unearned Revenue	587	973
Latin America
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	2,092	2,038
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	11,749	10,840
Policyholder account balances	5,100	5,071
Policyholder Dividends Payable	0	0
Unearned Premiums	1	123
Unearned Revenue	740	762
EMEA
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	1,787	1,701
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	5,215	5,221
Policyholder account balances	12,037	11,730
Policyholder Dividends Payable	6	5
Unearned Premiums	23	23
Unearned Revenue	555	509
MetLife Holdings
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	2,712	3,656
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	78,048	74,999
Policyholder account balances	28,858	28,966
Policyholder Dividends Payable	494	601
Unearned Premiums	154	164
Unearned Revenue	188	193
Corporate & Other
SEC Schedule, 12-16, Insurance Companies, Supplementary Insurance Information [Line Items]
DAC and VOBA	31	25
Future Policy Benefits, Other Policy-Related Balances and Policyholder Dividend Obligation	1,475	1,565
Policyholder account balances	(16)	(19)
Policyholder Dividends Payable	0	0
Unearned Premiums	0	0
Unearned Revenue	$ 0	$ 0