Earnings Per Common Share (Earnings Per Common Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,096,925,583	1,064,252,898
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	0
Exercise or issuance of stock-based awards	6,959,822	0
Weighted average common stock outstanding for diluted earnings per common share	1,103,885,405	1,064,252,898
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 995	$ (134)
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	6	24
Less: Preferred stock dividends	30	30
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	959	(188)
Basic	$ 0.87	$ (0.17)
Diluted	$ 0.87	$ (0.17)
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	(3)	14
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	(3)	14
Basic	$ 0.00	$ 0.01
Diluted	$ 0.00	$ 0.01
Net Income (Loss):
Net income (loss)	992	(120)
Less: Net income (loss) attributable to noncontrolling interests	6	24
Less: Preferred stock dividends	30	30
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 956	$ (174)
Basic	$ 0.87	$ (0.16)
Diluted	$ 0.87	$ (0.16)