Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
Revenues	$ 151,570	$ 123,737	$ 285,720	$ 233,088
Cost of goods sold	121,885	103,662	234,209	198,382
Gross profit	29,685	20,075	51,511	34,706
Selling, general and administrative expenses	18,573	17,195	35,861	33,123
Research and development expenses	1,783	1,663	3,258	3,357
Amortization of intangible assets	44	44	88	88
Operating income (loss)	9,285	1,173	12,304	(1,862)
Interest expense	60	55	127	111
Interest income	(330)	(245)	(711)	(402)
Income (loss) before income taxes	9,555	1,363	12,888	(1,571)
Income tax provision	2,134	405	2,692	166
Net income (loss)	$ 7,421	$ 958	$ 10,196	$ (1,737)
Earnings (loss) per share:
Basic (in dollars per share)	$ 0.64	$ 0.08	$ 0.88	$ (0.15)
Diluted (in dollars per share)	$ 0.64	$ 0.08	$ 0.87	$ (0.15)
Weighted average shares:
Basic (in shares)	11,621	11,570	11,617	11,560
Diluted (in shares)	11,681	11,632	11,673	11,560
Dividends per share (in dollars per share)	$ 0.26	$ 0.26	$ 0.52	$ 0.52