Quarterly Results of Operations (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Results of Operations (Unaudited)
Total revenues	$ 16,746	$ 20,457	$ 17,148	$ 15,911	$ 12,690	$ 12,338	$ 14,139	$ 13,098	$ 70,262	$ 52,265	$ 40,657
Total expenses	15,225	15,152	15,430	14,429	12,710	11,953	11,775	11,915	60,236	48,353	45,018
Income (loss) from continuing operations, net of income tax	1,127	3,571	1,199	1,054	66	317	1,536	828	6,951	2,747	(2,336)
Income (loss) from discontinued operations, net of income tax	25	5	31	(41)	19	3	11	6	20	39	58
Net income (loss)	1,152	3,576	1,230	1,013	85	320	1,547	834	6,971	2,786	(2,278)
Less: Net income (loss) attributable to noncontrolling interests	(4)	(6)	(7)	7	3	4	(10)	(1)	(10)	(4)	(32)
Net income (loss) attributable to MetLife, Inc.	1,156	3,582	1,237	1,006	82	316	1,557	835	6,981	2,790	(2,246)
Less: Preferred stock dividends	31	30	31	30	31	30	31	30	122	122	122
Preferred stock redemption premium	0	0	0	146	0	0	0	0	146	0	0
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 1,125	$ 3,552	$ 1,206	$ 830	$ 51	$ 286	$ 1,526	$ 805	$ 6,713	$ 2,668	$ (2,368)
Basic earnings per common share:
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	$ 1.04	$ 3.35	$ 1.11	$ 0.82	$ 0.03	$ 0.33	$ 1.84	$ 0.97	$ 6.32	$ 2.98	$ (2.96)
Income (loss) from discontinued operations, net of income tax, attributable to MetLife, Inc.	$ 0.02	$ 0.00	$ 0.03	$ (0.04)	$ 0.02	$ 0.00	$ 0.01	$ 0.01	$ 0.02	$ 0.04	$ 0.07
Net income (loss) attributable to MetLife, Inc.	$ 1.09	$ 3.38	$ 1.17	$ 0.95	$ 0.08	$ 0.36	$ 1.90	$ 1.02
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 1.06	$ 3.35	$ 1.14	$ 0.78	$ 0.05	$ 0.33	$ 1.85	$ 0.98	$ 6.34	$ 3.02	$ (2.89)
Diluted earnings per common share:
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders	$ 1.04	$ 3.33	$ 1.10	$ 0.82	$ 0.03	$ 0.32	$ 1.83	$ 0.96	$ 6.27	$ 2.96	$ (2.96)
Income (loss) from discontinued operations, net of income tax, attributable to MetLife, Inc.	$ 0.02	$ 0.00	$ 0.03	$ (0.04)	$ 0.02	$ 0.00	$ 0.01	$ 0.01	$ 0.02	$ 0.04	$ 0.07
Net income (loss) attributable to MetLife, Inc.	$ 1.08	$ 3.36	$ 1.16	$ 0.94	$ 0.08	$ 0.36	$ 1.87	$ 1.01
Net income (loss) available to MetLife, Inc.'s common shareholders	$ 1.06	$ 3.33	$ 1.13	$ 0.78	$ 0.05	$ 0.32	$ 1.84	$ 0.97	$ 6.29	$ 3.00	$ (2.89)