Earnings Per Common Share (Earnings Per Common Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Weighted Average Shares
Weighted average common stock outstanding for basic earnings per common share	1,125,703,588	1,126,922,641
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	3,385,696
Exercise or issuance of stock-based awards	10,057,530	10,157,701
Weighted average common stock outstanding for diluted earnings per common share	1,135,761,118	1,140,466,038
Income (Loss) from Continuing Operations
Income (loss) from continuing operations, net of income tax	$ 2,163	$ 1,342
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	5	11
Less: Preferred stock dividends	30	30
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.’s common shareholders	2,128	1,301
Basic	$ 1.89	$ 1.15
Diluted	$ 1.87	$ 1.14
Income (Loss) from Discontinued Operations
Income (loss) from discontinued operations, net of income tax	0	(3)
Less: Income (loss) from discontinued operations, net of income tax, attributable to noncontrolling interests	0	0
Income (loss) from discontinued operations, net of income tax, available to MetLife, Inc.’s common shareholders	0	(3)
Basic	$ 0.00	$ 0.00
Diluted	$ 0.00	$ 0.00
Net Income (Loss)
Net income (loss)	2,163	1,339
Less: Net income (loss) attributable to noncontrolling interests	5	11
Less: Preferred stock dividends	30	30
Net income (loss) available to MetLife, Inc.’s common shareholders	$ 2,128	$ 1,298
Basic	$ 1.89	$ 1.15
Diluted	$ 1.87	$ 1.14