Investments (Changes in Net Unrealized Investment Gains Losses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance, beginning of period	$ 14,419
Fixed maturity securities on which noncredit OTTI losses have been recognized	101
Unrealized investment gains (losses) during the year	(1,332)
Unrealized investment gains (losses) relating to [Abstract]
Insurance liability gain (loss) recognition	436
DAC and VOBA related to noncredit OTTI losses recognized in accumulated other comprehensive income (loss)	(10)
DAC and VOBA	243
Policyholder dividend obligation	229
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in accumulated other comprehensive income (loss)	(32)
Deferred income tax benefit (expense)	185
Net unrealized investment gains (losses)	14,239
Net unrealized investment gains (losses) attributable to noncontrolling interests	(2)
Balance, end of period	14,237
Changes in net unrealized investment gains (losses)	(180)
Changes in net unrealized investment gains (losses) attributable to noncontrolling interests	(2)
Changes in net unrealized investment gains (losses) attributable to MetLife, Inc.	$ (182)