Earnings Per Common Share (Earnings Per Common Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,104,892,638	1,065,041,874	1,099,496,305	1,063,991,836
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	1,886,275	0	628,758	0
Exercise or issuance of stock-based awards	10,517,925	0	8,756,239	5,963,399
Weighted average common stock outstanding for diluted earnings per common share	1,117,296,838	1,065,041,874	1,108,881,302	1,069,955,235
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 973	$ (957)	$ 2,476	$ 1,209
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	3	(3)	17	29
Less: Preferred stock dividends	30	30	91	91
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	940	(984)	2,368	1,089
Basic	$ 0.85	$ (0.92)	$ 2.15	$ 1.02
Diluted	$ 0.84	$ (0.92)	$ 2.14	$ 1.01
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	2	0	1	17
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	2	0	1	17
Basic	$ 0.00	$ 0.00	$ 0.00	$ 0.02
Diluted	$ 0.00	$ 0.00	$ 0.00	$ 0.02
Net Income (Loss):
Net income (loss)	975	(957)	2,477	1,226
Less: Net income (loss) attributable to noncontrolling interests	3	(3)	17	29
Less: Preferred stock dividends	30	30	91	91
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 942	$ (984)	$ 2,369	$ 1,106
Basic	$ 0.85	$ (0.92)	$ 2.15	$ 1.04
Diluted	$ 0.84	$ (0.92)	$ 2.14	$ 1.03
Earnings Per Share, Diluted, Other Disclosures [Abstract]
Shares excluded from the calculation of diluted earnings per common share as the assumed exercise or issuance are anti-dilutive		5,928,114