Equity (Details 11) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other comprehensive income (loss):
Holding gains (losses) on investments arising during the year	$ 12,777	$ 13,945	$ 10,092
Income tax effect of holding gains (losses)	(4,738)	(4,783)	(3,516)
Reclassification adjustments for recognized holding (gains) losses included in current year income	53	755	(733)
Income tax effect of reclassification adjustments	(20)	(260)	255
Unrealized investment loss of subsidiary at the date of disposal	0	(105)	0
Income tax on unrealized investment loss of subsidiary at the date of disposal	0	37	0
Allocation of holding (gains) losses on investments relating to other policyholder amounts	(3,675)	(6,248)	(2,598)
Income tax effect of allocation of holding (gains) losses to other policyholder amounts	1,362	2,146	905
Allocation of holding (gains) losses on investments relating to other policyholder amounts of subsidiary at the date of disposal	0	93	0
Income tax effect of allocation of holding (gains) losses on investments relating to other policyholder amounts of subsidiary at the date of disposal	0	(33)	0
Net unrealized investment gains (losses), net of income tax	5,759	5,547	4,405
Foreign currency translation adjustments, net of income tax expense (benefit)	110	(146)	(354)
Foreign currency translation adjustments of subsidiary at the date of disposal	0	(7)	0
Defined benefit plans adjustment, net of income tax expense (benefit)	(546)	(494)	96
Other comprehensive income (loss), net of income tax	5,323	4,900	4,147
Other comprehensive income (loss) attributable to noncontrolling interests	(9)	38	(5)
Other comprehensive income (loss) attributable to MetLife, Inc., excluding cumulative effect of change in accounting principle	5,314	4,938	4,142
Cumulative effect of change in accounting principle, net of income tax	0	0	52
Other comprehensive income (loss) attributable to MetLife, Inc.	5,314	4,938	4,194
Other Comprehensive Income (Loss), Effect of Change in Accounting Principle, Taxes	0	0	27
Other comprehensive income (loss), Foreign currency translation adjustments, taxes	(249)	162	(226)
Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax	$ (296)	$ (266)	$ 69