Investments (Changes in Net Unrealized Investment Gains Losses) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Changes In Net Unrealized Investment Gains Losses Included In Accumulated Other Comprehensive Loss [Abstract]
Balance at January 1,	$ 3,704	$ 6,339	$ 4,868
Fixed maturity securities on which noncredit OTTI losses have been recognized	83	107	266
Unrealized investment gains (losses) during the year	8,313	(11,205)	4,679
Unrealized investment gains (losses) relating to:
Future policy benefits	(1,354)	4,510	(1,625)
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	(8)	(7)	(21)
DAC, VOBA and DSI	(197)	510	(129)
Policyholder dividend obligation	(1,384)	2,057	(909)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	(26)	(35)	(86)
Deferred income tax benefit (expense)	1,858	(1,428)	704
Net unrealized investment gains (losses)	7,273	3,704	6,339
Net unrealized investment gains (losses) attributable to noncontrolling interests	0	0	0
Balance at December 31,	7,273	3,704	6,339
Change in net unrealized investment gains (losses)	3,569	(2,635)	1,471
Change in net unrealized investment gains (losses) attributable to noncontrolling interests	0	0	0
Change in net unrealized investment gains (losses) attributable to Metropolitan Life Insurance Company	$ 3,569	$ (2,635)	$ 1,471