Property, Plant and Equipment - Additional Information (Details) $ in Millions	12 Months Ended
	Sep. 30, 2019 USD ($)
Property Plant And Equipment [Line Items]
Accelerated depreciation	$ 39
Selling, General and Administrative Expenses [Member] | Unallocated and other [Member]
Property Plant And Equipment [Line Items]
Accelerated depreciation	1
Machinery and Equipment [Member]
Property Plant And Equipment [Line Items]
Accelerated depreciation	$ 38