Employee Benefit Plans - Amounts Recognized in Consolidated Balance Sheets (Detail) - USD ($) $ in Millions	Sep. 30, 2019	Sep. 30, 2018
Defined Benefit Plan Disclosure [Line Items]
Noncurrent liabilities	$ (91)	$ (118)
Pension Benefits [Member] | U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets		10
Current liabilities	(3)
Noncurrent liabilities	(3)	(4)
Pension Benefits [Member] | Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Noncurrent assets	19	21
Current liabilities	(1)	(1)
Noncurrent liabilities	(43)	(70)
Postretirement Benefits [Member] | U.S. Defined Benefit Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities	(3)	(3)
Noncurrent liabilities	(25)	(26)
Postretirement Benefits [Member] | Foreign Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Current liabilities		(1)
Noncurrent liabilities	$ (20)	$ (18)