Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014	Dec. 31, 2013
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 22,167	$ 30,367
Fixed maturity securities with noncredit OTTI losses in AOCI	(50)	(112)	$ (218)
Total fixed maturity securities	22,117	30,255
Equity securities	620	608
Derivatives	1,804	1,761
Other	192	149
Subtotal	24,733	32,773
Future policy benefits	(1,309)	(2,886)
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	(4)	(4)
DAC, VOBA and DSI	(1,451)	(1,946)
Policyholder dividend obligation	(2,328)	(3,155)
Subtotal	(5,092)	(7,991)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	20	42
Deferred income tax benefit (expense)	(6,774)	(8,556)
Net unrealized investment gains (losses)	12,887	16,268
Net unrealized investment gains (losses) attributable to noncontrolling interests	(24)	(33)
Net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 12,863	$ 16,235