Segment Information (Total Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Segment Reporting Information [Line Items]
Total assets	$ 698,451	$ 719,892
U.S.
Segment Reporting Information [Line Items]
Total assets	251,231	255,428
Asia
Segment Reporting Information [Line Items]
Total assets	142,033	136,928
Latin America
Segment Reporting Information [Line Items]
Total assets	73,973	79,670
EMEA
Segment Reporting Information [Line Items]
Total assets	29,024	30,500
MetLife Holdings
Segment Reporting Information [Line Items]
Total assets	173,351	183,160
Corporate & Other
Segment Reporting Information [Line Items]
Total assets	$ 28,839	$ 34,206