Accounts Payable, Accrued Liabilities and Other Liabilities - Components of Other Long-Term Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Payables And Accruals [Abstract]
Employee benefit plan liabilities	$ 91	$ 118
Non-current tax liabilities	12	19
Other accrued liabilities	103	115
Total	$ 206	$ 252