Goodwill (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Goodwill [Line Items]
Goodwill	$ 9,590	$ 9,220	$ 9,217	$ 9,612
Impairment (5)	0	(260)	0
Goodwill, Impaired, Accumulated Impairment Loss	(680)	(680)	(680)	(680)
Goodwill Disposition	16	42
Japan
Goodwill [Line Items]
Goodwill	4,500	4,400	4,300
Corporate & Other
Goodwill [Line Items]
Goodwill	103	0	42	42
Goodwill, Impaired, Accumulated Impairment Loss	0	0	0	0
Goodwill Disposition	0	42
MetLife Holdings
Goodwill [Line Items]
Goodwill	887	887	887	887
Goodwill, Impaired, Accumulated Impairment Loss	(680)	(680)	(680)	$ (680)
Goodwill Disposition	0	0
Parent Company
Goodwill [Line Items]
Impairment (5)	$ 0	$ (147)	$ 0