Earnings Per Common Share (Earnings Per Common Share) (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Weighted Average Shares:
Weighted average common stock outstanding for basic earnings per common share									1,105,579,693	1,070,755,561	1,059,580,442
Incremental common shares from assumed:
Stock purchase contracts underlying common equity units									1,164,018	0	1,641,444
Exercise or issuance of stock-based awards									9,458,999	6,084,078	6,872,474
Weighted average common stock outstanding for diluted earnings per common share									1,116,202,710	1,076,839,639	1,068,094,360
Income (Loss) from Continuing Operations:
Income (loss) from continuing operations, net of income tax	$ 915	$ 973	$ 508	$ 995	$ 105	$ (957)	$ 2,300	$ (134)	$ 3,391	$ 1,314	$ 6,391
Less: Income (loss) from continuing operations, net of income tax, attributable to noncontrolling interests									25	38	(8)
Less: Preferred stock dividends	31	30	31	30	31	30	31	30	122	122	122
Preferred stock redemption premium									0	0	146
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders									3,244	1,154	6,131
Basic	$ 0.78	$ 0.85	$ 0.43	$ 0.87	$ 0.06	$ (0.92)	$ 2.13	$ (0.17)	$ 2.94	$ 1.08	$ 5.79
Diluted	$ 0.77	$ 0.84	$ 0.43	$ 0.87	$ 0.06	$ (0.92)	$ 2.12	$ (0.17)	$ 2.91	$ 1.08	$ 5.74
Income (Loss) from Discontinued Operations:
Income (loss) from discontinued operations, net of income tax	1	2	2	(3)	31	0	3	14	2	48	24
Less: Income (loss) from discontinued operations, net of income tax, attributable to noncontrolling interests									0	0	0
Income (loss) from discontinued operations, net of income tax, available to MetLife, Inc.'s common shareholders									2	48	24
Basic	$ 0.00	$ 0	$ 0	$ 0.00	$ 0.03	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.04	$ 0.02
Diluted	$ 0.00	$ 0	$ 0	$ 0.00	$ 0.03	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.04	$ 0.02
Net Income (Loss):
Net income (loss)	916	975	510	992	136	(957)	2,303	(120)	3,393	1,362	6,415
Less: Net income (loss) attributable to noncontrolling interests	8	3	8	6	9	(3)	8	24	25	38	(8)
Less: Preferred stock dividends	31	30	31	30	31	30	31	30	122	122	122
Preferred stock redemption premium									0	0	146
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 877	$ 942	$ 471	$ 956	$ 96	$ (984)	$ 2,264	$ (174)	$ 3,246	$ 1,202	$ 6,155
Basic	$ 0.78	$ 0.85	$ 0.43	$ 0.87	$ 0.09	$ (0.92)	$ 2.13	$ (0.16)	$ 2.94	$ 1.12	$ 5.81
Diluted	$ 0.77	$ 0.84	$ 0.43	$ 0.87	$ 0.09	$ (0.92)	$ 2.12	$ (0.16)	$ 2.91	$ 1.12	$ 5.76