CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenues	$ 517,180	$ 448,716	$ 395,911
Cost of goods sold	430,204	383,361	345,142
Gross profit	86,976	65,355	50,769
Selling, general and administrative expenses	69,950	66,768	61,524
Research and development expenses	6,327	6,717	6,906
Amortization of intangible assets	177	205	355
Insurance proceeds	(950)	0	0
Restructuring, separation and other expenses, net	11	787	1,322
Operating income (loss)	11,461	(9,122)	(19,338)
Other income (Note F)	0	(747)	(2,029)
Interest expense	230	207	168
Interest income	(1,103)	(883)	(558)
Income (loss) before income taxes	12,334	(7,699)	(16,919)
Income tax provision (benefit)	2,444	(547)	(7,433)
Net income (loss)	$ 9,890	$ (7,152)	$ (9,486)
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.85	$ (0.62)	$ (0.83)
Diluted (in dollars per share)	$ 0.85	$ (0.62)	$ (0.83)
Weighted average shares:
Basic (in shares)	11,571	11,507	11,453
Diluted (in shares)	11,634	11,507	11,453
Dividends per share (in dollars per share)	$ 1.04	$ 1.04	$ 1.04