Consolidated Statements of Comprehensive Income - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ 521	$ 730	$ 881
Change in net unrealized gains (losses) on:
Investments with no other-than-temporary impairment, net of tax provision (benefit) of $(32), $27 and $(42)	(215)	64	(89)
Investments with other-than-temporary impairment, net of tax provision (benefit) of $(8), $46 and $13	(26)	89	25
Change in net unrealized gains (losses) on investments	(241)	153	(64)
Change in net unrealized gains (losses) on financial guaranty variable interest entities' liabilities with recourse, net of tax	2	0	0
Other, net of tax provision (benefit) of $(2), $2, and (5)	(8)	14	(24)
Other comprehensive income (loss)	(247)	167	(88)
Comprehensive income (loss)	$ 274	$ 897	$ 793