Earnings Per Common Share (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,064,688,383	1,059,751,486	1,063,560,105	1,058,795,981
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	4,015,640	0	3,282,889
Exercise or issuance of stock-based awards	5,291,235	7,208,779	5,971,776	7,832,099
Weighted average common stock outstanding for diluted earnings per common share	1,069,979,618	1,070,975,905	1,069,531,881	1,069,910,969
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 2,300	$ 1,062	$ 2,166	$ 1,986
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	8	(7)	32	0
Less: Preferred stock dividends	31	31	61	61
Preferred stock redemption premium	0	0	0	146
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	2,261	1,038	2,073	1,779
Basic	$ 2.13	$ 0.98	$ 1.95	$ 1.68
Diluted	$ 2.12	$ 0.97	$ 1.93	$ 1.66
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	3	31	17	(9)
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	3	31	17	(9)
Basic	$ 0.00	$ 0.03	$ 0.02	$ (0.01)
Diluted	$ 0.00	$ 0.03	$ 0.02	$ (0.01)
Net Income (Loss):
Net income (loss)	2,303	1,093	2,183	1,977
Less: Net income (loss) attributable to noncontrolling interests	8	(7)	32	0
Less: Preferred stock dividends	31	31	61	61
Preferred stock redemption premium	0	0	0	146
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 2,264	$ 1,069	$ 2,090	$ 1,770
Basic	$ 2.13	$ 1.01	$ 1.97	$ 1.67
Diluted	$ 2.12	$ 1.00	$ 1.95	$ 1.65