Stockholders' Equity (Schedule of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		$ 3,117	$ 3,351	$ 3,148
Other comprehensive income (loss)		(7)	4	(1)
Cumulative effect of change in accounting principle	[1]				$ 0
Balance		2,811	3,117	3,351
Comprehensive (loss) income, net of taxes		146	99	455
Post-Retirement Benefit Plans, net of taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(16)	(21)	(17)
Other comprehensive income (loss)		(9)	9	(4)
Cumulative effect of change in accounting principle					(4)
Balance		(25)	(16)	(21)
Other comprehensive income (loss), tax expense (benefit)		(3)	3	(3)
Translation Adjustment, net of taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(14)	(9)	(12)
Other comprehensive income (loss)		2	(5)	3
Balance		(12)	(14)	(9)
Other comprehensive income (loss), tax expense (benefit)		1	(2)	2
Total Stockholders' Accumulated Other Comprehensive Loss, net of taxes
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Balance		(30)	(30)	(29)
Cumulative effect of change in accounting principle	[1]				$ (4)
Balance		(37)	(30)	(30)
Comprehensive (loss) income, net of taxes		$ (7)	$ 4	$ (1)

[1] In 2018, the Company adopted ASU No. 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income, and made a $4 million adjustment to reclassify stranded tax effects in Accumulated Other Comprehensive Loss to Retained Earnings.