Fair Value Measurements - Schedule of Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions		Dec. 31, 2016	Sep. 30, 2016
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations			$ (4)
Total		$ 2
Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Total		6
Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations			(4)
Total		(4)
Other Current Assets
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Foreign Currency Forward Exchange Contracts	[1],[2]	6
Other Current Assets | Level 2
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Foreign Currency Forward Exchange Contracts	[2]	6
Other Non-Current Liabilities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations	[3]	(4)	(4)
Other Non-Current Liabilities | Level 3
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Contractual Obligations	[3]	$ (4)	$ (4)

[1] Includes $15 million and $9 million of foreign exchange derivative contracts in asset and liability positions, respectively.

[2] The fair value of the foreign currency forward exchange contracts is based on dealer quotes of market forward rates and reflects the amount that the Company would receive or pay at their maturity dates for contracts involving the same currencies and maturity dates.

[3] This represents purchase obligations and contingent consideration related to the Company’s various acquisitions. This is based on a discounted cash flow 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.