Business Basis of Presentation and Summary of Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Assets:
Other invested assets, principally at estimated fair value	$ 20,172	$ 23,581
Deferred policy acquisition costs and value of business acquired	25,105	24,619	25,147	24,465
Liabilities:
Future policy benefits	184,141	184,275
Deferred income tax liability	6,375	6,395
Equity:
Retained earnings	24,640	24,814
Accumulated other comprehensive income (loss)	7,266	6,083
Total MetLife, Inc.'s stockholders' equity	58,666	57,519
Noncontrolling interests	344	370
Total equity	59,010	57,889	48,298	47,218
Previously Reported [Member]
Assets:
Other invested assets, principally at estimated fair value		23,628
Deferred policy acquisition costs and value of business acquired		27,971
Liabilities:
Future policy benefits		184,252
Deferred income tax liability		7,535
Equity:
Retained earnings		27,289
Accumulated other comprehensive income (loss)		5,886
Total MetLife, Inc.'s stockholders' equity		59,797
Noncontrolling interests		374
Total equity		60,171		48,996
Restatement Adjustment [Member]
Assets:
Other invested assets, principally at estimated fair value		(47)
Deferred policy acquisition costs and value of business acquired		(3,352)
Liabilities:
Future policy benefits		23
Deferred income tax liability		(1,140)
Equity:
Retained earnings		(2,475)
Accumulated other comprehensive income (loss)		197
Total MetLife, Inc.'s stockholders' equity		(2,278)
Noncontrolling interests		(4)
Total equity		$ (2,282)