Shareholders' (Deficiency) Equity (Changes in Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2018	Mar. 31, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ (1,746)		$ (1,519)	$ (1,746)	$ (1,519)
Other Comprehensive Income before Reclassifications					63	(161)
Reclassifications					0	1
Other Comprehensive Income	$ 30	33	$ (165)	5	63	(160)
Ending balance	(1,683)		(1,679)		(1,683)	(1,679)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(1,724)		(1,484)	(1,724)	(1,484)
Other Comprehensive Income before Reclassifications					63	(161)
Reclassifications					0	0
Other Comprehensive Income					63	(161)
Ending balance	(1,661)		(1,645)		(1,661)	(1,645)
Defined Benefit Pension
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		(14)		(26)	(14)	(26)
Other Comprehensive Income before Reclassifications					0	0
Reclassifications					0	1
Other Comprehensive Income					0	1
Ending balance	(14)		(25)		(14)	(25)
Deferred Loss on Derivatives
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Beginning balance		$ (8)		$ (9)	(8)	(9)
Other Comprehensive Income before Reclassifications					0	0
Reclassifications					0	0
Other Comprehensive Income					0	0
Ending balance	$ (8)		$ (9)		$ (8)	$ (9)