Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Allowance for doubtful accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	$ 592	$ 520
Additions (Reductions) Charged to Expense	(80)	39
Additions (Reductions) Charged to Other Accounts	0	0
Deductions	(263)	33
Valuation allowances and reserves, ending balance	249	592
Inventory obsolescence reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	3,335
Additions (Reductions) Charged to Expense	518	517
Additions (Reductions) Charged to Other Accounts	(151)	(106)
Deductions	(26)	(632)
Valuation allowances and reserves, ending balance	3,676	3,335
Inventory LIFO reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	8,296
Additions (Reductions) Charged to Expense	(10)	(75)
Additions (Reductions) Charged to Other Accounts	0	0
Deductions	0	0
Valuation allowances and reserves, ending balance	8,286	8,296
Deferred tax valuation allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	7,557	8,400
Additions (Reductions) Charged to Expense	(2,362)	(1,817)
Additions (Reductions) Charged to Other Accounts	134	974
Deductions	0	0
Valuation allowances and reserves, ending balance	5,329	7,557
Workers’ compensation reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance	181	136
Additions (Reductions) Charged to Expense	703	395
Additions (Reductions) Charged to Other Accounts	0	0
Deductions	(338)	(350)
Valuation allowances and reserves, ending balance	$ 546	181
Accounting Standards Update 2014-09 | Inventory obsolescence reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance		3,556
Accounting Standards Update 2014-09 | Inventory LIFO reserve
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Valuation allowances and reserves, beginning balance		$ 8,371