Shareholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (1,746)	$ (1,519)
Other Comprehensive Income before Reclassifications	33	5
Currency Translation Adjustments	33	5
Other Comprehensive Income	33	5
Ending balance	(1,713)	(1,514)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1,724)	(1,484)
Other Comprehensive Income before Reclassifications	33	5
Other Comprehensive Income		5
Ending balance	(1,691)	(1,479)
Defined Benefit Pension
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(14)	(26)
Other Comprehensive Income before Reclassifications	0	0
Other Comprehensive Income	0	0
Ending balance	(14)	(26)
Deferred Loss on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(8)	(9)
Other Comprehensive Income before Reclassifications	0	0
Other Comprehensive Income	0	0
Ending balance	$ (8)	$ (9)