Quarterly Results of Operations (Unaudited) (Quarterly Results of Operations) (Details) (USD $) In Millions, except Per 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
Quarterly Results of Operations (Unaudited)
Total revenues	$ 18,458	$ 16,337	$ 15,721	$ 17,683	$ 17,333	$ 16,503	$ 18,398	$ 15,916	$ 68,199	$ 68,150	$ 70,241
Total expenses	17,190	15,361	15,160	16,436	17,810	17,513	15,060	16,325	64,147	66,708	61,057
Income (loss) from continuing operations, net of income tax	915	973	508	995	105	(957)	2,300	(134)	3,391	1,314	6,391
Income (loss) from discontinued operations, net of income tax	1	2	2	(3)	31	0	3	14	2	48	24
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)
Net income (loss) attributable to MetLife, Inc.	908	972	502	986	127	(954)	2,295	(144)	3,368	1,324	6,423
Less: Preferred stock dividends	31	30	31	30	31	30	31	30	122	122	122
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 earnings per common share:
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	$ 0.78	$ 0.85	$ 0.43	$ 0.87	$ 0.06	$ (0.92)	$ 2.13	$ (0.17)	$ 2.94	$ 1.08	$ 5.79
Income (loss) from discontinued operations, net of income tax, attributable to MetLife, Inc.	$ 0.00	$ 0	$ 0	$ 0.00	$ 0.03	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.04	$ 0.02
Net income (loss) attributable to MetLife, Inc.	$ 0.81	$ 0.88	$ 0.46	$ 0.90	$ 0.12	$ (0.90)	$ 2.16	$ (0.14)
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 0.78	$ 0.85	$ 0.43	$ 0.87	$ 0.09	$ (0.92)	$ 2.13	$ (0.16)	$ 2.94	$ 1.12	$ 5.81
Diluted earnings per common share:
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	$ 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, net of income tax, attributable to MetLife, Inc.	$ 0.00	$ 0	$ 0	$ 0.00	$ 0.03	$ 0.00	$ 0.00	$ 0.01	$ 0.00	$ 0.04	$ 0.02
Net income (loss) attributable to MetLife, Inc.	$ 0.80	$ 0.87	$ 0.45	$ 0.89	$ 0.12	$ (0.90)	$ 2.14	$ (0.14)
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 0.77	$ 0.84	$ 0.43	$ 0.87	$ 0.09	$ (0.92)	$ 2.12	$ (0.16)	$ 2.91	$ 1.12	$ 5.76