Long-Term Debt - Narrative (Details) - USD ($)	12 Months Ended
	Sep. 30, 2018	Oct. 31, 2001
U.S. Revolver
Line of Credit Facility [Line Items]
Revolving credit facility	$ 75,000,000
Revolving credit facility borrowings, outstanding amount	$ 0
Max leverage, ratio of indebtedness to consolidated earnings before (EBITDA), not exceed	2.75
Fixed charge coverage, ratio of consolidated EBITDA, less income taxes, capital expenditures, principal debt payments and interest charges (at least)	1.25
Amount of credit facility remaining borrowing capacity	$ 51,900,000
Percentage of voting capital stock pledged as collateral	100.00%
Non-domestic subsidiaries of voting capital stock	65.00%
U.S. Revolver | Maximum
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.25%
U.S. Revolver | Federal Funds Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	0.50%
U.S. Revolver | Eurocurrency Rate
Line of Credit Facility [Line Items]
Basis spread on variable rate	1.00%
Industrial Development Revenue Bonds
Line of Credit Facility [Line Items]
Borrowings		$ 8,000,000
Reimbursement agreement requires annual redemptions	$ 400,000
Interest rate	1.72%
The Third Amendment | U.S. Revolver
Line of Credit Facility [Line Items]
Cash collateral percent of outstanding debt (at least)	102.00%
Cash collateral pledged balance	$ 25,100,000
Financial Standby Letter of Credit | U.S. Revolver
Line of Credit Facility [Line Items]
Guarantee liability	$ 23,100,000