Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 881	$ 1,056	$ 1,088
Unrealized holding gains (losses) arising during the period on:
Investments with no other-than-temporary impairment, net of tax provision (benefit) of $(34), $(36) and $80	(71)	(93)	196
Investments with other-than-temporary impairment, net of tax provision (benefit) of $(5), $(23) and $(9)	(9)	(43)	(20)
Unrealized holding gains (losses) arising during the period, net of tax	(80)	(136)	176
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $(10), $(7) and $(21)	(16)	(10)	(41)
Change in net unrealized gains (losses) on investments	(64)	(126)	217
Other, net of tax provision	(24)	(7)	(7)
Other comprehensive income (loss)	(88)	(133)	210
Comprehensive income (loss)	$ 793	$ 923	$ 1,298