Investments (Changes in Net Unrealized Investment Gains Losses) (Details) $ in Millions	3 Months Ended
	Mar. 31, 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	(15)
Unrealized investment gains (losses) during the period	10,733
Unrealized investment gains (losses) relating to [Abstract]
Future policy benefits	(1,252)
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	2
DAC, VOBA and DSI	(627)
Policyholder dividend obligation	(803)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	12
Deferred income tax benefit (expense)	(2,674)
Net unrealized investment gains (losses)	17,149
Net unrealized investment gains (losses) attributable to noncontrolling interests	22
Balance, end of period	17,171
Change in net unrealized investment gains (losses)	5,376
Change in net unrealized investment gains (losses) attributable to noncontrolling interests	22
Change in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 5,398