Condensed Consolidated Statements of Comprehensive Income (unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statement of Comprehensive Income [Abstract]
Net income	$ 69	$ 161	$ 265	$ 433
Change in net unrealized gains (losses) on:
Investments with no other-than-temporary impairment, net of tax provision (benefit) of $7, $(12), $51 and $(43)	33	(59)	275	(250)
Investments with other-than-temporary impairment, net of tax provision (benefit) of $(2), $(2), $(14) and $(2)	(9)	(9)	(52)	(5)
Change in net unrealized gains (losses) on investments	24	(68)	223	(255)
Change in net unrealized gains (losses) on financial guaranty variable interest entities' liabilities with recourse resulting from a change in the instrument-specific credit risk, net of tax	0	(3)	4	(1)
Other, net of tax provision (benefit)	0	(3)	(1)	(6)
Other comprehensive income (loss)	24	(74)	226	(262)
Comprehensive income (loss)	$ 93	$ 87	$ 491	$ 171