Accounts Payable, Accrued Liabilities and Other Liabilities - Components of Other Long-Term Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016
Payables And Accruals [Abstract]
Employee benefit plan liabilities	$ 122	$ 173
Non-current tax liabilities	19	19
Other accrued liabilities	104	93
Total	$ 245	$ 285