Investments (Net Unrealized Investment Gains Losses) (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Components of net unrealized gains (losses) included in accumulated other comprehensive income
Fixed maturity securities AFS	$ 37,287	$ 30,050
Fixed maturity securities AFS with noncredit OTTI losses included in AOCI	0	33
Total fixed maturity securities AFS	37,287	30,083
Derivatives	5,357	2,209
Other	442	310
Subtotal	43,086	32,602
Future policy benefits	(2,218)	(1,019)
DAC, VOBA and DSI	(3,670)	(2,716)
Policyholder dividend obligation	(2,798)	(2,020)
Subtotal	(8,686)	(5,755)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	0	(4)
Deferred income tax benefit (expense)	(8,469)	(6,846)
Net unrealized investment gains (losses)	25,931	19,997
Net unrealized investment gains (losses) attributable to noncontrolling interests	(18)	(16)
Net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 25,913	$ 19,981