Receivables, net - Additional Information (Details)	3 Months Ended		6 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2018	Mar. 31, 2017	Sep. 30, 2017
Accounts, Notes, Loans and Financing Receivable [Line Items]
Document Period End Date			Mar. 31, 2018
Credit Concentration Risk [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Percentage of net sales from major customer	40.30%	37.90%	38.00%	36.90%
Percentage Of Accounts Receivable Three Major Customers	29.90%		29.90%		36.20%