Shareholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss)) (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 of Tax [Roll Forward]
Beginning balance			$ (1,519)	$ (1,610)
Other Comprehensive Income before Reclassifications			(170)	165
Reclassifications			1	(44)
Other Comprehensive Income (Loss)	$ (9)	$ 88	(169)	121
Ending balance	(1,688)	(1,489)	(1,688)	(1,489)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(1,484)	(1,614)
Other Comprehensive Income before Reclassifications			(170)	165
Reclassifications			0	0
Other Comprehensive Income (Loss)			(170)	165
Ending balance	(1,654)	(1,449)	(1,654)	(1,449)
Defined Benefit Pension
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(26)	13
Other Comprehensive Income before Reclassifications			0	0
Reclassifications			1	(44)
Other Comprehensive Income (Loss)			1	(44)
Ending balance	(25)	(31)	(25)	(31)
Deferred Loss on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance			(9)	(9)
Other Comprehensive Income before Reclassifications			0	0
Reclassifications			0	0
Other Comprehensive Income (Loss)			0	0
Ending balance	$ (9)	$ (9)	$ (9)	$ (9)