Consolidated Statements Of Comprehensive Loss - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Consolidated Statements Of Comprehensive Loss [Abstract]
Net loss	$ (38)	$ (80)	$ (775)	$ (293)
Pension settlement costs, net of tax	12		48
Other comprehensive income (loss), net of tax	(32)	(61)	(10)	(50)
Net current-period other comprehensive income (loss)	(20)	(61)	38	(50)
Comprehensive loss	$ (58)	$ (141)	$ (737)	$ (343)