Comprehensive Income - Schedule of Accumulated Other Comprehensive Loss (Detail) $ in Millions	9 Months Ended
	Jun. 30, 2019 USD ($)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ (320)
Ending balance	(133)
Foreign Currency Translation Loss
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(184)	[1]
Other comprehensive loss	(17)	[1]
Ending balance	(201)	[1]
Minimum Pension Liability Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(9)
Other comprehensive loss	0
Ending balance	(9)
Deferred Losses On Derivative Financial Instruments
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	3
Other comprehensive loss	(12)
Ending balance	(9)
Accumulated Other Comprehensive Loss, net
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(190)
Other comprehensive loss	(29)
Ending balance	$ (219)

[1] Includes historical foreign currency translation related to certain intra-entity transactions.