Note 12 - Other Financial Data - Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Sep. 30, 2017
Accounts receivable, net:
Accounts receivable	$ 50,719	$ 40,485
Less allowance for doubtful accounts	(264)	(201)
Total	50,455	40,284
Inventories:
Raw materials	34,353	51,808
Work in process	3,953	2,637
Finished goods	24,850	27,408
Total	63,156	81,853
Other current assets:
Prepaid insurance	2,957	3,796
Income tax receivable		925
Other	1,114	1,228
Total	4,071	5,949
Other assets:
Cash surrender value of life insurance policies	9,425	9,026
Capitalized financing costs, net	73	105
Other	151	203
Total	9,649	9,334
Property, plant and equipment, net:
Land and land improvements	14,428	12,177
Buildings	53,991	50,373
Machinery and equipment	156,352	153,484
Construction in progress	6,388	5,641
Property, plant and equipment, gross	231,159	221,675
Less accumulated depreciation	(127,882)	(123,005)
Total	103,277	98,670
Accrued expenses:
Salaries, wages and related expenses	3,524	5,520
Customer rebates	776	1,015
Property taxes	524	1,384
Workers' compensation	115	116
Other	558	632
Total	5,497	8,667
Other liabilities:
Deferred compensation	10,704	9,276
Deferred Tax Liabilities, Net, Noncurrent	5,833	8,103
Total	$ 16,537	$ 17,379