Quarterly Results of Operations (Unaudited) (Quarterly Results of Operations) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Quarterly Results of Operations (Unaudited)
Total revenues	$ 10,585	$ 9,857	$ 9,252	$ 9,037	$ 9,884	$ 8,018	$ 8,632	$ 8,766	$ 38,731	$ 35,300	$ 36,046
Total expenses	9,224	8,017	8,210	7,889	9,106	7,758	7,771	7,843	33,340	32,478	32,348
Income (loss) from continuing operations, net of income tax	979	1,303	749	828	580	242	646	673	3,859	2,141	2,643
Income (loss) from discontinued operations, net of income tax	0	0	0	(3)	1	0	0	0	(3)	1	40
Net income (loss)	979	1,303	749	825	581	242	646	673	3,856	2,142	2,683
Less: Net income (loss) attributable to noncontrolling interests	1	(7)	0	1	(4)	(5)	3	(1)	(5)	(7)	2
Net income (loss) attributable to Metropolitan Life Insurance Company	$ 978	$ 1,310	$ 749	$ 824	$ 585	$ 247	$ 643	$ 674	$ 3,861	$ 2,149	$ 2,681