Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Statements of Comprehensive Income (Loss)
Net income (loss)	$ 71	$ (45)	$ (116)	$ (289)
Unrealized gains (losses) on available-for-sale securities: [Abstract]
Unrealized gains (losses) arising during the period	39	(4)	164	(61)
Provision (benefit) for income taxes	(11)	0	29	5
Total	50	(4)	135	(66)
Reclassification adjustments for (gains) losses included in net income (loss)	8	(2)	(15)	(3)
Available-for-sale securities with other-than-temporary impairments: [Abstract]
Other-than-temporary impairments and unrealized gains (losses) arising during the period	(32)	25	(2)	48
Reclassification adjustments for (gains) losses included in net income (loss)	(42)	2	(5)	3
Foreign currency translation: [Abstract]
Foreign currency translation gains (losses)	1	0	1	2
Instrument-specific credit risk of liabilities measured at fair value: [Abstract]
Unrealized gains (losses) arising during the period	(27)	28	(27)	(4)
Reclassification adjustments for (gains) losses included in net income (loss)	3	0	26	0
Total other comprehensive income (loss)	(39)	49	113	(20)
Comprehensive income (loss)	$ 32	$ 4	$ (3)	$ (309)