Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities AFS	$ 24,197	$ 30,050
Fixed maturity securities AFS with noncredit OTTI losses included in AOCI	0	33
Total fixed maturity securities AFS	24,197	30,083
Derivatives	6,336	2,209
Other	524	310
Subtotal	31,057	32,602
Future policy benefits	546	(1,019)
DAC, VOBA and DSI	(2,759)	(2,716)
Policyholder dividend obligation	(1,677)	(2,020)
Subtotal	(3,890)	(5,755)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	0	(4)
Deferred income tax benefit (expense)	(6,781)	(6,846)
Net unrealized investment gains (losses)	20,386	19,997
Net unrealized investment gains (losses) attributable to noncontrolling interests	(17)	(16)
Net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 20,369	$ 19,981