Investments (Details 15) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance, beginning of period	$ 8,674	$ 3,122	$ (1,338)
Cumulative effect of change in accounting principle, net of income tax	0	0	52
Fixed maturity securities on which noncredit OTTI losses have been recognized	363	(123)	242
Unrealized investment gains (losses) during the year	12,467	14,823	9,117
Unrealized investment gains (losses) of subsidiaries at the date of disposal	0	(105)	0
Unrealized investment gains (losses) relating to [Abstract]
Insurance liability gain (loss) recognition	(2,053)	(3,406)	(554)
Insurance liability gain (loss) recognition of subsidiaries at the date of disposal	0	82	0
DAC and VOBA related to noncredit OTTI losses recognized in accumulated other comprehensive income (loss)	(28)	9	(33)
DAC and VOBA	(685)	(808)	(1,135)
DAC and VOBA of subsidiaries at the date of disposal	0	11	0
Policyholder dividend obligation	(909)	(2,043)	(876)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in accumulated other comprehensive income (loss)	(117)	39	(73)
Deferred income tax benefit (expense)	(3,279)	(2,936)	(2,283)
Deferred income tax benefit (expense) of subsidiaries at the date of disposal	0	4	0
Net unrealized investment gains (losses)	14,433	8,669	3,119
Net unrealized investment gains (losses) attributable to noncontrolling interests	(14)	5	3
Balance, end of period	14,419	8,674	3,122
Changes in net unrealized investment gains (losses)	5,759	5,547	4,457
Changes in net unrealized investment gains (losses) attributable to noncontrolling interests	(14)	5	3
Changes in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 5,745	$ 5,552	$ 4,460