Investments (Changes in Net Unrealized Investment Gains Losses) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2015 USD ($)
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance, beginning of period	$ 16,235
Fixed maturity securities on which noncredit OTTI losses have been recognized	13
Unrealized investment gains (losses) during the period	(7,976)
Unrealized investment gains (losses) relating to [Abstract]
Future policy benefits	2,703
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	4
DAC, VOBA and DSI	490
Policyholder dividend obligation	846
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	(16)
Deferred income tax benefit (expense)	1,346
Net unrealized investment gains (losses)	13,645
Net unrealized investment gains (losses) attributable to noncontrolling interests	(11)
Balance, end of period	13,634
Change in net unrealized investment gains (losses)	(2,590)
Change in net unrealized investment gains (losses) attributable to noncontrolling interests	(11)
Change in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ (2,601)