Segment Information (Total Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Total assets	$ 719,892	$ 898,764
Separate account assets	205,001	195,578
Separate account liabilities	205,001	195,578
U.S.
Segment Reporting Information [Line Items]
Total assets	255,428	253,926
Separate account assets	81,243	85,950
Separate account liabilities	81,243	85,950
Asia
Segment Reporting Information [Line Items]
Total assets	136,928	120,656
Separate account assets	10,032	8,020
Separate account liabilities	10,032	8,020
Latin America
Segment Reporting Information [Line Items]
Total assets	79,670	67,233
Separate account assets	56,218	48,455
Separate account liabilities	56,218	48,455
EMEA
Segment Reporting Information [Line Items]
Total assets	30,500	25,596
Separate account assets	5,975	4,329
Separate account liabilities	5,975	4,329
MetLife Holdings
Segment Reporting Information [Line Items]
Total assets	183,160	183,832
Separate account assets	51,533	48,823
Separate account liabilities	51,533	48,823
Corporate & Other
Segment Reporting Information [Line Items]
Total assets	34,206	247,521
Separate account assets	0	1
Separate account liabilities	$ 0	$ 1