Stockholders' Equity (Schedule of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		$ 3,038	$ 3,244	$ 3,117	$ 3,350
Translation adjustment	[1]	(1)	1	1	(2)
Ending balance		2,883	3,196	2,883	3,196
Translation adjustment, net of tax expense (benefit)				1	(1)
Total Stockholders’ Accumulated Other Comprehensive Loss, net of taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance		(28)	(33)	(30)	(30)
Ending balance		(29)	(32)	(29)	(32)
Post-Retirement Benefit Plans, net of taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance				(16)	(20)
Translation adjustment				0	0
Ending balance		(16)	(20)	(16)	(20)
Translation Adjustment, net of taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance				(14)	(10)
Translation adjustment				1	(2)
Ending balance		$ (13)	$ (12)	$ (13)	$ (12)

[1] Translation adjustment is presented net of tax expense of $1 million and tax benefit of $1 million for the nine months ended September 30, 2019 and 2018, respectively.