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		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues
Net investment income	$ 4,719	$ 5,094	$ 10,919	$ 10,406
Expenses
Policyholder benefits and claims	8,911	9,121	18,015	17,358
Other expenses	4,775	4,699	9,096	8,789
Income (loss) from continuing operations before provision for income tax	3,338	1,510	2,929	2,794
Provision for income tax expense (benefit)	1,038	448	763	808
Income (loss) from continuing operations, net of income tax	2,300	1,062	2,166	1,986
Net income (loss)	2,303	1,093	2,183	1,977
Net income (loss) attributable to MetLife, Inc.	2,295	1,100	2,151	1,977
Net income (loss) available to MetLife, Inc.'s common shareholders	2,264	1,069	2,090	1,770
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic	$ 2.13	$ 0.98	$ 1.95	$ 1.68
Diluted	$ 2.12	$ 0.97	$ 1.93	$ 1.66
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic	$ 2.13	$ 1.01	$ 1.97	$ 1.67
Diluted	$ 2.12	$ 1.00	$ 1.95	$ 1.65
Impact of income (loss) from discontinued real estate operations		2		3
Impact of net investment income from discontinued real estate operations				4
Tax effect of impact of income (loss) from discontinued real estate operations				1
Previously Reported [Member]
Revenues
Net investment income		5,096		10,410
Expenses
Policyholder benefits and claims		9,119		17,350
Other expenses		4,495		8,397
Income (loss) from continuing operations before provision for income tax		1,718		3,198
Provision for income tax expense (benefit)		519		946
Income (loss) from continuing operations, net of income tax		1,199		2,252
Net income (loss)		1,230		2,243
Net income (loss) attributable to MetLife, Inc.		1,237		2,243
Net income (loss) available to MetLife, Inc.'s common shareholders		1,206		2,036
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic		$ 1.11		$ 1.93
Diluted		$ 1.10		$ 1.91
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic		$ 1.14		$ 1.92
Diluted		$ 1.13		$ 1.90
Restatement Adjustment [Member]
Revenues
Net investment income		(2)		(4)
Expenses
Policyholder benefits and claims		2		8
Other expenses		204		392
Income (loss) from continuing operations before provision for income tax		(208)		(404)
Provision for income tax expense (benefit)		(71)		(138)
Income (loss) from continuing operations, net of income tax		(137)		(266)
Net income (loss)		(137)		(266)
Net income (loss) attributable to MetLife, Inc.		(137)		(266)
Net income (loss) available to MetLife, Inc.'s common shareholders		$ (137)		$ (266)
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic		$ (0.13)		$ (0.25)
Diluted		$ (0.13)		$ (0.25)
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic		$ (0.13)		$ (0.25)
Diluted		$ (0.13)		$ (0.25)