Stockholders' Equity (Schedule of Components of Other Comprehensive Income (Loss), Net) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Stockholders' Equity Note [Abstract]
Foreign currency translation gain (loss), gross amount	$ 13	$ 45
Foreign currency translation gain (loss), income tax (provision) benefit	(6)	4
Foreign currency translation gain (loss), net	7	49
Gain (loss) on cash flow hedges, gross amount	(3)	(2)
Gain (loss) on cash flow hedges, income tax (provision) benefit	0	1
Gain (loss) on cash flow hedges, net	(3)	(1)
Pension and postretirement benefits gain (loss), gross amount	0	1
Pension and postretirement benefits gain (loss), income tax (provision) benefit	0	0
Pension and postretirement benefits gain (loss), net	0	1
Other Comprehensive Income (Loss), before Tax	10	44
Income tax (provision) benefit	(6)	5
Total other comprehensive income (loss), net of tax	$ 4	$ 49