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, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share	1,125,165,772	1,104,892,638	1,126,280,770	1,099,496,305
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units	4,572,193	1,886,275	3,904,760	628,758
Exercise or issuance of stock-based awards	11,308,766	10,517,925	10,662,053	8,756,239
Weighted average common stock outstanding for diluted earnings per common share	1,141,046,731	1,117,296,838	1,140,847,583	1,108,881,302
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 2,094	$ 973	$ 4,812	$ 2,476
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests	0	3	21	17
Less: Preferred stock dividends	30	30	91	91
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	2,064	940	4,700	2,368
Basic	$ 1.83	$ 0.85	$ 4.17	$ 2.15
Diluted	$ 1.81	$ 0.84	$ 4.12	$ 2.14
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)	2,094	975	4,809	2,477
Less: Net income (loss) attributable to noncontrolling interests	0	3	21	17
Less: Preferred stock dividends	30	30	91	91
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 2,064	$ 942	$ 4,697	$ 2,369
Basic	$ 1.83	$ 0.85	$ 4.17	$ 2.15
Diluted	$ 1.81	$ 0.84	$ 4.12	$ 2.14