Consolidated Statements Of Comprehensive Income (Loss) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Consolidated Statements Of Comprehensive Income (Loss) [Abstract]
Net income (loss)	$ (5,317)	$ (18)	$ (5,404)	$ 2
Other comprehensive income, net of tax	9	71	17	70
Comprehensive income (loss)	$ (5,308)	$ 53	$ (5,387)	$ 72