Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Weighted Average Shares
Weighted average common stock outstanding for basic earnings per common share	1,117,807,514	1,127,986,031	1,120,801,928	1,126,876,090
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	3,756,390	0	3,571,043
Exercise or issuance of stock-based awards	10,584,264	10,519,694	10,320,897	10,338,697
Weighted average common stock outstanding for diluted earnings per common share	1,128,391,778	1,142,262,115	1,131,122,825	1,140,785,830
Income (Loss) from Continuing Operations
Income (loss) from continuing operations, net of income tax	$ 1,119	$ 1,376	$ 3,282	$ 2,718
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	4	10	9	21
Less: Preferred stock dividends	31	31	61	61
Preferred stock repurchase premium	42	0	42	0
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.’s common shareholders	$ 1,042	$ 1,335	$ 3,170	$ 2,636
Basic	$ 0.93	$ 1.18	$ 2.83	$ 2.34
Diluted	$ 0.92	$ 1.17	$ 2.80	$ 2.31
Income (Loss) from Discontinued Operations
Income (loss) from discontinued operations, net of income tax	$ 0	$ 0	$ 0	$ (3)
Less: Income (loss) from discontinued operations, net of income tax, attributable to noncontrolling interests	0	0	0	0
Income (loss) from discontinued operations, net of income tax, available to MetLife, Inc.’s common shareholders	$ 0	$ 0	$ 0	$ (3)
Basic	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Diluted	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Net Income (Loss)
Net income (loss)	$ 1,119	$ 1,376	$ 3,282	$ 2,715
Less: Net income (loss) attributable to noncontrolling interests	4	10	9	21
Less: Preferred stock dividends	31	31	61	61
Preferred stock repurchase premium	42	0	42	0
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 1,042	$ 1,335	$ 3,170	$ 2,633
Basic	$ 0.93	$ 1.18	$ 2.83	$ 2.34
Diluted	$ 0.92	$ 1.17	$ 2.80	$ 2.31