Investments (Changes in Net Unrealized Investment Gains Losses) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance, beginning of period	$ 11,773
Fixed maturity securities on which noncredit OTTI losses have been recognized	17
Unrealized investment gains (losses) during the period	20,067
Unrealized investment gains (losses) relating to:
Future policy benefits	(4,247)
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	(2)
DAC, VOBA and DSI	(1,107)
Policyholder dividend obligation	(1,560)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	(4)
Deferred income tax benefit (expense)	(4,322)
Net unrealized investment gains (losses)	20,615
Net unrealized investment gains (losses) attributable to noncontrolling interests	20
Balance, end of period	20,635
Change in net unrealized investment gains (losses)	8,842
Change in net unrealized investment gains (losses) attributable to noncontrolling interests	20
Change in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 8,862