Stockholders' Equity (Schedule of Adjustments to Accumulated Other Comprehensive Income (Loss), Net) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Accumulated Other Comprehensive Income (Loss), net [Line Items]
As of December 31, 2017			$ (177)
Other comprehensive income (loss) before reclassifications			(21)
Amounts reclassified from accumulated other comprehensive income (loss)			(1)
Income tax (provision) benefit	$ 6	$ 7	11	$ 7
As of June 30, 2018	(188)		(188)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss), net [Line Items]
As of December 31, 2017			(176)
Other comprehensive income (loss) before reclassifications			(27)
Amounts reclassified from accumulated other comprehensive income (loss)			0
Income tax (provision) benefit			10
As of June 30, 2018	(193)		(193)
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			5
Amounts reclassified from accumulated other comprehensive income (loss)			(1)
Income tax (provision) benefit			1
As of June 30, 2018	7		7
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 June 30, 2018	$ (2)		$ (2)