Earnings Per Common Share (Earnings Per Common Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Weighted Average Shares
Weighted average common stock outstanding for basic earnings per common share	1,118,856,041	1,125,165,772	1,120,130,708	1,126,280,770
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	4,572,193	0	3,904,760
Exercise or issuance of stock-based awards	11,085,040	11,308,766	10,575,611	10,662,053
Weighted average common stock outstanding for diluted earnings per common share	1,129,941,081	1,141,046,731	1,130,706,319	1,140,847,583
Income (Loss) from Continuing Operations
Income (loss) from continuing operations, net of income tax	$ 1,198	$ 2,094	$ 4,480	$ 4,812
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	(5)	0	4	21
Less: Preferred stock dividends	6	30	67	91
Preferred stock repurchase premium	0	0	42	0
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.’s common shareholders	$ 1,197	$ 2,064	$ 4,367	$ 4,700
Basic	$ 1.07	$ 1.83	$ 3.90	$ 4.17
Diluted	$ 1.06	$ 1.81	$ 3.86	$ 4.12
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)	$ 1,198	$ 2,094	$ 4,480	$ 4,809
Less: Net income (loss) attributable to noncontrolling interests	(5)	0	4	21
Less: Preferred stock dividends	6	30	67	91
Preferred stock repurchase premium	0	0	42	0
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 1,197	$ 2,064	$ 4,367	$ 4,697
Basic	$ 1.07	$ 1.83	$ 3.90	$ 4.17
Diluted	$ 1.06	$ 1.81	$ 3.86	$ 4.12