Investments (Details 15) (USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2012
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance, beginning of period	$ 8,674
Fixed maturity securities on which noncredit OTTI losses have been recognized	283
Unrealized investment gains (losses) during the year	12,586
Unrealized investment gains (losses) relating to [Abstract]
Insurance liability gain (loss) recognition	(2,906)
DAC and VOBA related to noncredit OTTI losses recognized in accumulated other comprehensive income (loss)	(22)
DAC and VOBA	(816)
Policyholder dividend obligation	(990)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in accumulated other comprehensive income (loss)	(91)
Deferred income tax benefit (expense)	(2,958)
Net unrealized investment gains (losses)	13,760
Net unrealized investment gains (losses) attributable to noncontrolling interests	(8)
Balance, end of period	13,752
Changes in net unrealized investment gains (losses)	5,086
Changes in net unrealized investment gains (losses) attributable to noncontrolling interests	(8)
Changes in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ 5,078