Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 1,056	$ 1,088	$ 808
Unrealized holding gains (losses) arising during the period on:
Investments with no other-than-temporary impairment, net of tax provision (benefit) of $(36), $80 and $(106)	(93)	196	(309)
Investments with other-than-temporary impairment, net of tax provision (benefit) of $(23), $(9) and $(17)	(43)	(20)	(35)
Unrealized holding gains (losses) arising during the period, net of tax	(136)	176	(344)
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(7), $(21) and $5	(10)	(41)	14
Change in net unrealized gains on investments	(126)	217	(358)
Other, net of tax provision	(7)	(7)	3
Other comprehensive income (loss)	(133)	210	(355)
Comprehensive income (loss)	$ 923	$ 1,298	$ 453