Fair Value Measurements - Schedule of Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions		Sep. 30, 2016	Sep. 30, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations		$ (4)	$ (1)
Other Current Liabilities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations	[1]	(4)	(1)
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations		(4)	(1)
Level 3 | Other Current Liabilities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations	[1]	$ (4)	$ (1)

[1] This represents purchase obligations and contingent consideration related to the Company’s various acquisitions. This is based on a probability weighted performance approach and it is adjusted to fair value on a recurring basis and any adjustments are included as a component of operating income in the statement of operations. These amounts were mainly calculated using unobservable inputs such as future earnings performance of the Company’s various acquisitions and the expected timing of the payment.