Shareholders' Equity (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2017	Mar. 31, 2017	Jun. 30, 2016	Mar. 31, 2016	Jun. 30, 2017	Jun. 30, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (1,577)	$ (1,610)	$ (1,507)	$ (1,641)	$ (1,610)	$ (1,641)
Other Comprehensive Income before Reclassifications		74		133
Reclassifications		(41)		1
Other Comprehensive Income (Loss)	(10)	33	(9)	134	33	134
Ending balance	(1,577)	(1,577)		(1,507)	(1,577)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(1,540)	(1,614)	(1,470)	(1,602)	(1,614)	(1,602)
Other Comprehensive Income before Reclassifications		74		132
Reclassifications		0		0
Other Comprehensive Income (Loss)		74		132
Ending balance		(1,540)		(1,470)
Defined Benefit Pension
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	(28)	13	(28)	(29)	13	(29)
Other Comprehensive Income before Reclassifications		0		1
Reclassifications		(41)		0
Other Comprehensive Income (Loss)		(41)		1
Ending balance		(28)		(28)
Deferred Loss on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance	$ (9)	(9)	$ (9)	(10)	$ (9)	$ (10)
Other Comprehensive Income before Reclassifications		0		0
Reclassifications		0		1
Other Comprehensive Income (Loss)		0		1
Ending balance		$ (9)		$ (9)