Earnings Per Common Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,065,041,874	1,060,199,513	1,063,991,836	1,059,253,798
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	0	0	2,188,593
Exercise or issuance of stock-based awards	0	6,001,186	5,963,399	7,221,794
Weighted average common stock outstanding for diluted earnings per common share	1,065,041,874	1,066,200,699	1,069,955,235	1,068,664,185
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ (957)	$ 3,442	$ 1,209	$ 5,428
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	(3)	(6)	29	(6)
Less: Preferred stock dividends	30	30	91	91
Preferred stock redemption premium	0	0	0	146
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	(984)	3,418	1,089	5,197
Basic	$ (0.92)	$ 3.22	$ 1.02	$ 4.91
Diluted	$ (0.92)	$ 3.20	$ 1.01	$ 4.86
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	0	8	17	(1)
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	8	17	(1)
Basic	$ 0.00	$ 0.01	$ 0.02	$ 0.00
Diluted	$ 0.00	$ 0.01	$ 0.02	$ 0.00
Net Income (Loss):
Net income (loss)	(957)	3,450	1,226	5,427
Less: Net income (loss) attributable to noncontrolling interests	(3)	(6)	29	(6)
Less: Preferred stock dividends	30	30	91	91
Preferred stock redemption premium	0	0	0	146
Net income (loss) available to MetLife, Inc.'s common shareholders	$ (984)	$ 3,426	$ 1,106	$ 5,196
Basic	$ (0.92)	$ 3.23	$ 1.04	$ 4.91
Diluted	$ (0.92)	$ 3.21	$ 1.03	$ 4.86
Earnings Per Common Share Textuals [Abstract]
Shares excluded from the calculation of diluted earnings per common share as the assumed exercise or issuance are anti-dilutive	5,928,114