Stockholders' Equity (Schedule of Adjustments to Accumulated Other Comprehensive Income (Loss), Net) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Accumulated Other Comprehensive Income (Loss), net [Line Items]
As of December 31, 2017			$ (177)
Other comprehensive income (loss) before reclassifications			(48)
Amounts reclassified from accumulated other comprehensive income (loss)			(1)
Income tax (provision) benefit	$ (4)	$ (2)	7	$ 5
As of September 30, 2018	(219)		(219)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss), net [Line Items]
As of December 31, 2017			(176)
Other comprehensive income (loss) before reclassifications			(58)
Amounts reclassified from accumulated other comprehensive income (loss)			0
Income tax (provision) benefit			6
As of September 30, 2018	(228)		(228)
Gain (Loss) from Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss), net [Line Items]
As of December 31, 2017			2
Other comprehensive income (loss) before reclassifications			9
Amounts reclassified from accumulated other comprehensive income (loss)			(1)
Income tax (provision) benefit			1
As of September 30, 2018	11		11
Pension and Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss), net [Line Items]
As of December 31, 2017			(3)
Other comprehensive income (loss) before reclassifications			1
Amounts reclassified from accumulated other comprehensive income (loss)			0
Income tax (provision) benefit			0
As of September 30, 2018	$ (2)		$ (2)