Stockholders' Equity (Schedule of Adjustments to Accumulated Other Comprehensive Income (Loss), Net) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of the beginning of the period	$ (358)	$ (348)	$ (165)
Other comprehensive income (loss) before reclassifications	174	(18)	(189)
Amounts reclassified from accumulated other comprehensive income (loss)	(5)	(4)	3
Income tax (provision) benefit	12	12	3
Balance as of the end of the period	(177)	(358)	(348)
Unrealized Gain (Loss) on Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of the beginning of the period	1	1	1
Other comprehensive income (loss) before reclassifications	0	0	0
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Income tax (provision) benefit	(1)	0	0
Balance as of the end of the period	0	1	1
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of the beginning of the period	(350)	(339)	(151)
Other comprehensive income (loss) before reclassifications	162	(22)	(193)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Income tax (provision) benefit	12	11	5
Balance as of the end of the period	(176)	(350)	(339)
Gain (Loss) from Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of the beginning of the period	3	(2)	(4)
Other comprehensive income (loss) before reclassifications	4	7	(2)
Amounts reclassified from accumulated other comprehensive income (loss)	(4)	(2)	5
Income tax (provision) benefit	(1)	0	(1)
Balance as of the end of the period	2	3	(2)
Pension and Postretirement Benefits [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance as of the beginning of the period	(12)	(8)	(11)
Other comprehensive income (loss) before reclassifications	8	(3)	6
Amounts reclassified from accumulated other comprehensive income (loss)	(1)	(2)	(2)
Income tax (provision) benefit	2	1	(1)
Balance as of the end of the period	$ (3)	$ (12)	$ (8)