Investments (Net Unrealized Investment Gains Losses) (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Components of net unrealized investment gains (losses) included in accumulated other comprehensive loss
Fixed maturity securities	$ 15,374	$ 8,521	$ 19,120
Fixed maturity securities with noncredit OTTI losses in AOCI	(66)	(149)	(256)
Total fixed maturity securities	15,308	8,372	18,864
Equity securities	173	83	(13)
Derivatives	1,649	361	1,052
Short-term investments	0	0	(2)
Other	87	5	18
Subtotal	17,217	8,821	19,919
Future policy benefits	(1,964)	(610)	(5,120)
DAC and VOBA related to noncredit OTTI losses recognized in AOCI	(3)	5	12
DAC, VOBA and DSI	(918)	(721)	(1,231)
Policyholder dividend obligation	(3,155)	(1,771)	(3,828)
Subtotal	(6,040)	(3,097)	(10,167)
Deferred income tax benefit (expense) related to noncredit OTTI losses recognized in AOCI	25	51	86
Deferred income tax benefit (expense)	(3,928)	(2,070)	(3,498)
Net unrealized investment gains (losses)	7,274	3,705	6,340
Net unrealized investment gains (losses) attributable to noncontrolling interests	(1)	(1)	(1)
Net unrealized investment gains (losses) attributable to Metropolitan Life Insurance Company	$ 7,273	$ 3,704	$ 6,339	$ 4,868