Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Consolidated Statements Of Comprehensive Income (Loss) [Abstract]
Net income (loss)	$ 15	$ (345)	$ (352)	$ (5,749)
Other comprehensive income (loss), net of tax	155	8	(182)	25
Comprehensive income (loss)	$ 170	$ (337)	$ (534)	$ (5,724)