Summary of Significant Accounting Policies - Additional Information (Details)	12 Months Ended
	Sep. 30, 2019 USD ($) Customer	Sep. 30, 2018 USD ($)
Significant Accounting Policies [Line Items]
Cash and cash equivalents held by foreign subsidiaries and branch offices	$ 7,000,000
Minimum credit limit	30 days
Extended credit terms for trade receivables	60 days
Number of customers affiliated with common parent | Customer	2
Goodwill impairment	$ 0
Shipping and handling costs	46,059,000	$ 51,913,000
Income tax, Interest or penalties incurred	0	0
Shipping and Handling
Significant Accounting Policies [Line Items]
Shipping and handling costs	500,000	500,000
Customer one
Significant Accounting Policies [Line Items]
Trade account and financing receivable due	$ 6,700,000	$ 9,000,000
Customer one | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue	19.70%	10.40%
Customer two
Significant Accounting Policies [Line Items]
Trade account and financing receivable due	$ 3,600,000
Customer two | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue	5.20%
Customer three
Significant Accounting Policies [Line Items]
Trade account and financing receivable due	$ 8,500,000
Customer three | Customer Concentration Risk | Sales Revenue, Net
Significant Accounting Policies [Line Items]
Percentage of company revenue	20.00%