Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 146	$ 297	$ 205	$ 498
Unrealized holding gains (losses) arising during the period on:
Investments with no other-than-temporary impairment, net of tax provision (benefit) of $31, $(54), $62 and $(53)	84	(136)	179	(118)
Investments with other-than-temporary impairment, net of tax provision (benefit) of $(3), $(1), $(13) and $(3)	(6)	(6)	(23)	(8)
Unrealized holding gains (losses) arising during the period, net of tax	78	(142)	156	(126)
Less: reclassification adjustment for gains (losses) included in net income (loss), net of tax provision (benefit) of $4, $(4), $0 and $2	5	(5)	(1)	5
Change in net unrealized gains on investments	73	(137)	157	(131)
Other, net of tax provision	(9)	6	(11)	0
Other comprehensive income (loss)	64	(131)	146	(131)
Comprehensive income (loss)	$ 210	$ 166	$ 351	$ 367