Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,090.4	1,100.8
Incremental common shares from assumed:
Incremental common shares from assumed exercise or issuance of stock-based awards	8.3	7.8
Weighted average common stock outstanding for diluted earnings per common share	1,098.7	1,108.6
Net Income (Loss):
Net income (loss)	$ 829	$ 2,203
Less: Net income (loss) attributable to noncontrolling interests	3	2
Less: Preferred stock dividends	6	6
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 820	$ 2,195
Basic	$ 0.75	$ 1.99
Diluted	$ 0.75	$ 1.98