Income Taxes (Schedule of Reconciliation of Unrecognized Tax Benefits Included in Uncertain Tax Positions) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	$ 114		$ 158		$ 228		$ 119	$ 114	$ 158
As of the beginning of the year	114		158		228
Increases in tax positions for the current year	14		9		13
Increases in tax positions for prior years(1)	4	[1]	11		76
Decreases in tax positions for prior years	(7)		(9)		(126)
Decreases due to settlements	(6)		(55)		(33)
As of the end of the year	119		114		158
Total uncertain tax positions that if recognized would impact the effective tax rate							100	87	144
Total amount of interest expense (benefit) and penalties recognized in the consolidated statements of operations(2)	6		(16)	[2]	(12)	[2]
Total amount of interest expense and penalties recognized in the consolidated balance sheets							38	$ 26	$ 43
Decreases in interest and penalties due to settlements			$ (1)		$ (12)
Nilit [Member]
Income Tax Contingency [Line Items]
Unrecognized Tax Benefits	4						$ 4
As of the end of the year	$ 4

[1] Includes uncertain tax positions related to the Nilit acquisition (Note 4) of $4 million for the year ended December 31, 2017.

[2] This amount reflects interest on uncertain tax positions and release of certain tax positions as a result of audit closure that was reflected in the consolidated statements of operations. In addition, for the years ended December 31, 2016 and 2015, the Company also paid an additional $1 million and $12 million, respectively, of previously accrued amounts due to settlements of tax examinations.