Business Basis of Presentation and Summary of Significant Accounting Policies (Details 1) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues
Net investment income	$ 5,517	$ 4,252	$ 16,436	$ 14,658
Expenses
Policyholder benefits and claims	8,943	9,018	26,958	26,376
Other expenses	4,245	5,198	13,341	13,987
Income (loss) from continuing operations before provision for income tax	(1,010)	5,115	1,919	7,909
Provision for income tax expense (benefit)	(53)	1,673	710	2,481
Income (loss) from continuing operations, net of income tax	(957)	3,442	1,209	5,428
Net income (loss)	(957)	3,450	1,226	5,427
Net income (loss) attributable to MetLife, Inc.	(954)	3,456	1,197	5,433
Net income (loss) available to MetLife, Inc.'s common shareholders	(984)	3,426	1,106	5,196
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic	$ (0.92)	$ 3.22	$ 1.02	$ 4.91
Diluted	$ (0.92)	$ 3.20	$ 1.01	$ 4.86
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic	$ (0.92)	$ 3.23	$ 1.04	$ 4.91
Diluted	$ (0.92)	$ 3.21	$ 1.03	$ 4.86
Impact of income (loss) from discontinued real estate operations		4		5
Impact of net investment income from discontinued real estate operations				6
Tax effect of impact of income (loss) from discontinued real estate operations				1
Previously Reported [Member]
Revenues
Net investment income		4,253		14,663
Expenses
Policyholder benefits and claims		9,017		26,367
Other expenses		5,013		13,410
Income (loss) from continuing operations before provision for income tax		5,302		8,500
Provision for income tax expense (benefit)		1,734		2,680
Income (loss) from continuing operations, net of income tax		3,568		5,820
Net income (loss)		3,576		5,819
Net income (loss) attributable to MetLife, Inc.		3,582		5,825
Net income (loss) available to MetLife, Inc.'s common shareholders		3,552		5,588
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic		$ 3.35		$ 5.29
Diluted		$ 3.33		$ 5.24
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic		$ 3.35		$ 5.28
Diluted		$ 3.33		$ 5.23
Restatement Adjustment [Member]
Revenues
Net investment income		(1)		(5)
Expenses
Policyholder benefits and claims		1		9
Other expenses		185		577
Income (loss) from continuing operations before provision for income tax		(187)		(591)
Provision for income tax expense (benefit)		(61)		(199)
Income (loss) from continuing operations, net of income tax		(126)		(392)
Net income (loss)		(126)		(392)
Net income (loss) attributable to MetLife, Inc.		(126)		(392)
Net income (loss) available to MetLife, Inc.'s common shareholders		$ (126)		$ (392)
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic		$ (0.13)		$ (0.38)
Diluted		$ (0.13)		$ (0.38)
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic		$ (0.12)		$ (0.37)
Diluted		$ (0.12)		$ (0.37)