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
	Mar. 31, 2012	Mar. 31, 2011
Revenues
Net investment income	$ 6,200	$ 5,313
Expenses
Policyholder benefits and claims	9,104	8,237
Other expenses	4,321	4,090
Income (loss) from continuing operations before provision for income tax	(409)	1,285
Provision for income tax expense (benefit)	(275)	361
Income (loss) from continuing operations, net of income tax	(134)	924
Net income (loss)	(120)	884
Net income (loss) attributable to MetLife, Inc.	(144)	877
Net income (loss) available to MetLife, Inc.'s common shareholders	(174)	701
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic	$ (0.17)	$ 0.70
Diluted	$ (0.17)	$ 0.70
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic	$ (0.16)	$ 0.66
Diluted	$ (0.16)	$ 0.66
Impact of income (loss) from discontinued real estate operations		2
Previously Reported [Member]
Revenues
Net investment income		5,315
Expenses
Policyholder benefits and claims		8,231
Other expenses		3,902
Income (loss) from continuing operations before provision for income tax		1,481
Provision for income tax expense (benefit)		428
Income (loss) from continuing operations, net of income tax		1,053
Net income (loss)		1,013
Net income (loss) attributable to MetLife, Inc.		1,006
Net income (loss) available to MetLife, Inc.'s common shareholders		830
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic		$ 0.82
Diluted		$ 0.82
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic		$ 0.78
Diluted		$ 0.78
Restatement Adjustment [Member]
Revenues
Net investment income		(2)
Expenses
Policyholder benefits and claims		6
Other expenses		188
Income (loss) from continuing operations before provision for income tax		(196)
Provision for income tax expense (benefit)		(67)
Income (loss) from continuing operations, net of income tax		(129)
Net income (loss)		(129)
Net income (loss) attributable to MetLife, Inc.		(129)
Net income (loss) available to MetLife, Inc.'s common shareholders		$ (129)
Income (loss) from continuing operations, net of income tax, available to MetLife, Inc.'s common shareholders per common share:
Basic		$ (0.12)
Diluted		$ (0.12)
Net income (loss) available to MetLife, Inc.'s common shareholders per common share:
Basic		$ (0.12)
Diluted		$ (0.12)