Consolidated Statements Of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 4,020	$ 854	$ 5,385
Other comprehensive income (loss):
Unrealized investment gains (losses), net of related offsets	4,623	796	(7,449)
Unrealized gains (losses) on derivatives	(1,165)	573	589
Foreign currency translation adjustments	767	(363)	(1,624)
Defined benefit plans adjustment	144	131	354
Other comprehensive income (loss), before income tax	4,369	1,137	(8,130)
Income tax (expense) benefit related to items of other comprehensive income (loss)	(984)	(450)	2,203
Other comprehensive income (loss), net of income tax	3,385	687	(5,927)
Comprehensive income (loss)	7,405	1,541	(542)
Less: Comprehensive income (loss) attributable to noncontrolling interest, net of income tax	14	92	32
Comprehensive income (loss) attributable to MetLife, Inc.	$ 7,391	$ 1,449	$ (574)