Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities AFS	$ 19,723	$ 11,356
Fixed maturity securities AFS with noncredit OTTI losses included in AOCI	29	25
Total fixed maturity securities AFS	19,752	11,381
Derivatives	2,114	2,127
Other	266	290
Subtotal	22,132	13,798
Future policy benefits	(222)	31
DAC, VOBA and DSI	(1,912)	(1,231)
Policyholder dividend obligation	(1,116)	(428)
Subtotal	(3,250)	(1,628)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	(4)	(3)
Deferred income tax benefit (expense)	(5,004)	(3,502)
Net unrealized investment gains (losses)	13,874	8,665
Net unrealized investment gains (losses) attributable to noncontrolling interests	(12)	(10)
Net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 13,862	$ 8,655