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, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,127,986,031	1,097,889,347	1,126,876,090	1,096,815,883
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	3,756,390	0	3,571,043	0
Exercise or issuance of stock-based awards	10,519,694	8,790,971	10,338,697	7,875,396
Weighted average common stock outstanding for diluted earnings per common share	1,142,262,115	1,106,680,318	1,140,785,830	1,104,691,279
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 1,376	$ 508	$ 2,718	$ 1,503
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	10	8	21	14
Less: Preferred stock dividends	31	31	61	61
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	1,335	469	2,636	1,428
Basic	$ 1.18	$ 0.43	$ 2.34	$ 1.30
Diluted	$ 1.17	$ 0.43	$ 2.31	$ 1.29
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	0	2	(3)	(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	2	(3)	(1)
Basic	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Diluted	$ 0.00	$ 0.00	$ 0.00	$ 0.00
Net Income (Loss):
Net income (loss)	1,376	510	2,715	1,502
Less: Net income (loss) attributable to noncontrolling interests	10	8	21	14
Less: Preferred stock dividends	31	31	61	61
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 1,335	$ 471	$ 2,633	$ 1,427
Basic	$ 1.18	$ 0.43	$ 2.34	$ 1.30
Diluted	$ 1.17	$ 0.43	$ 2.31	$ 1.29