Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2019	Mar. 31, 2018
Income Statement [Abstract]
Revenues	$ 123,737	$ 101,505	$ 233,088	$ 191,689
Cost of goods sold	103,662	89,084	198,382	168,713
Gross profit	20,075	12,421	34,706	22,976
Selling, general and administrative expenses	17,195	16,073	33,123	32,288
Research and development expenses	1,663	1,636	3,357	3,294
Amortization of intangible assets	44	44	88	117
Operating income (loss)	1,173	(5,332)	(1,862)	(12,723)
Other income	0	0	0	(507)
Interest expense	55	51	111	102
Interest income	(245)	(293)	(402)	(495)
Income (loss) before income taxes	1,363	(5,090)	(1,571)	(11,823)
Income tax expense (benefit)	405	(1,760)	166	(2,831)
Net income (loss)	$ 958	$ (3,330)	$ (1,737)	$ (8,992)
Income (loss) per share:
Basic (in dollars per share)	$ 0.08	$ (0.29)	$ (0.15)	$ (0.78)
Diluted (in dollars per share)	$ 0.08	$ (0.29)	$ (0.15)	$ (0.78)
Weighted average shares:
Basic (in shares)	11,570	11,509	11,560	11,503
Diluted (in shares)	11,632	11,509	11,560	11,503
Dividends per share (in dollars per share)	$ 0.26	$ 0.26	$ 0.52	$ 0.52