Comprehensive Loss - Schedule of Accumulated Other Comprehensive Loss (Detail) $ in Millions	6 Months Ended
	Mar. 31, 2017 USD ($)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 210
Ending balance	187
Foreign Currency Translation Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(201)	[1]
Other comprehensive loss	(13)	[1]
Ending balance	(214)	[1]
Minimum Pension Liability Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(17)
Ending balance	(17)
Deferred Losses On Derivative Financial Instruments
Accumulated Other Comprehensive Income Loss [Line Items]
Other comprehensive loss	(1)
Ending balance	(1)
Accumulated Other Comprehensive Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(218)
Other comprehensive loss	(14)
Ending balance	$ (232)

[1] Includes historical foreign currency translation related to certain intra-entity transactions that are no longer considered of a long-term investment nature.