Earnings Per Common Share (Earnings Per Common Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,097,889,347	1,064,688,383	1,096,815,883	1,063,560,105
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	0	0	0	0
Exercise or issuance of stock-based awards	8,790,971	5,291,235	7,875,396	5,971,776
Weighted average common stock outstanding for diluted earnings per common share	1,106,680,318	1,069,979,618	1,104,691,279	1,069,531,881
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 508	$ 2,300	$ 1,503	$ 2,166
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	8	8	14	32
Less: Preferred stock dividends	31	31	61	61
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	469	2,261	1,428	2,073
Basic	$ 0.43	$ 2.13	$ 1.30	$ 1.95
Diluted	$ 0.43	$ 2.12	$ 1.29	$ 1.93
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	2	3	(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	3	(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)	510	2,303	1,502	2,183
Less: Net income (loss) attributable to noncontrolling interests	8	8	14	32
Less: Preferred stock dividends	31	31	61	61
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 471	$ 2,264	$ 1,427	$ 2,090
Basic	$ 0.43	$ 2.13	$ 1.30	$ 1.97
Diluted	$ 0.43	$ 2.12	$ 1.29	$ 1.95