Consolidated Statements of Equity (Unaudited) - USD ($) $ in Millions	Total	Preferred Stock	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock at Cost	Accumulated Other Comprehensive Income (Loss)	Total MetLife, Inc.'s Stockholders' Equity	Noncontrolling Interests	Previously Reported	Previously Reported Preferred Stock	Previously Reported Common Stock	Previously Reported Additional Paid-in Capital	Previously Reported Retained Earnings	Previously Reported Treasury Stock at Cost	Previously Reported Accumulated Other Comprehensive Income (Loss)	Previously Reported Total MetLife, Inc.'s Stockholders' Equity	Previously Reported Noncontrolling Interests	Restatement Adjustment	Restatement Adjustment Retained Earnings	Restatement Adjustment Accumulated Other Comprehensive Income (Loss)	Restatement Adjustment Total MetLife, Inc.'s Stockholders' Equity
Beginning Balance at Dec. 31, 2016	$ 67,702	$ 0	$ 12	$ 30,944	$ 34,683	$ (3,474)	$ 5,366	$ 67,531	$ 171	$ 67,480	$ 0	$ 12	$ 30,944	$ 34,480	$ (3,474)	$ 5,347	$ 67,309	$ 171	$ 222	$ 203	$ 19	$ 222
Treasury stock acquired in connection with share repurchases	(2,305)					(2,305)		(2,305)
Stock-based compensation	122			122				122
Dividends on preferred stock	(58)				(58)			(58)
Dividends on common stock	(1,295)				(1,295)			(1,295)
Stockholders' Equity Note, Spinoff Transaction	(11,666)				(10,346)		(1,320)	(11,666)
Change in equity of noncontrolling interests	43							0	43
Net income (loss)	1,705				1,693			1,693	12
Other comprehensive income (loss), net of income tax	2,963						2,959	2,959	4							2,978					(19)
Ending Balance at Sep. 30, 2017	57,211	0	12	31,066	24,677	(5,779)	7,005	56,981	230	56,944									267
Beginning Balance at Dec. 31, 2016	67,702	0	12	30,944	34,683	(3,474)	5,366	67,531	171	67,480	0	12	30,944	34,480	(3,474)	5,347	67,309	171	$ 222	$ 203	$ 19	$ 222
Ending Balance at Dec. 31, 2017	58,870									$ 58,870	$ 0	$ 12	$ 31,111	$ 26,527	$ (6,401)	$ 7,427	$ 58,676	$ 194
Cumulative effects of changes in accounting principles, net of income tax (Note 1)	7				(905)		912	7
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest, Adjusted Balance	58,877	0	12	31,111	25,622	(6,401)	8,339	58,683	194
Preferred stock issuance	1,274			1,274				1,274
Treasury stock acquired in connection with share repurchases	(2,792)					(2,792)		(2,792)
Stock-based compensation	90			90				90
Dividends on preferred stock	(84)				(84)			(84)
Dividends on common stock	(1,263)				(1,263)			(1,263)
Change in equity of noncontrolling interests	(20)							0	(20)
Net income (loss)	3,066				3,056			3,056	10
Other comprehensive income (loss), net of income tax	(7,339)						(7,339)	(7,339)	0
Ending Balance at Sep. 30, 2018	$ 51,809	$ 0	$ 12	$ 32,475	$ 27,331	$ (9,193)	$ 1,000	$ 51,625	$ 184