Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,100,328,049	1,117,807,514	1,100,582,221	1,120,801,928
Incremental common shares from assumed:
Exercise or issuance of stock-based awards	8,800,389	10,584,264	8,292,739	10,320,897
Weighted average common stock outstanding for diluted earnings per common share	1,109,128,438	1,128,391,778	1,108,874,960	1,131,122,825
Net Income (Loss):
Net income (loss)	$ 114	$ 1,119	$ 2,317	$ 3,282
Less: Net income (loss) attributable to noncontrolling interests	4	4	6	9
Less: Preferred stock dividends	46	31	52	61
Preferred stock repurchase premium	0	42	0	42
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 64	$ 1,042	$ 2,259	$ 3,170
Basic	$ 0.06	$ 0.93	$ 2.05	$ 2.83
Diluted	$ 0.06	$ 0.92	$ 2.04	$ 2.80