CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
Revenues	$ 518,499	$ 517,180	$ 448,716
Cost of goods sold	423,924	430,204	383,361
Gross profit	94,575	86,976	65,355
Selling, general and administrative expenses	67,662	69,950	66,768
Research and development expenses	6,265	6,327	6,717
Amortization of intangible assets	177	177	205
Insurance proceeds	0	(950)	0
Restructuring and other, net	1,400	11	787
Operating income (loss)	19,071	11,461	(9,122)
Other income	(506)	0	(747)
Interest expense	228	230	207
Interest income	(981)	(1,103)	(883)
Income (loss) before income taxes	20,330	12,334	(7,699)
Income tax provision (benefit)	3,670	2,444	(547)
Net income (loss)	$ 16,660	$ 9,890	$ (7,152)
Earnings (loss) per share:
Basic (in dollars per share)	$ 1.43	$ 0.85	$ (0.62)
Diluted (in dollars per share)	$ 1.42	$ 0.85	$ (0.62)
Weighted average shares:
Basic (in shares)	11,624	11,571	11,507
Diluted (in shares)	11,693	11,634	11,507
Dividends per share (in dollars per share)	$ 1.04	$ 1.04	$ 1.04