Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]
Beginning balance at Sep. 30, 2019	$ 122,516	$ 675	$ 10,740	$ 396	$ 110,705
Beginning balance, shares at Sep. 30, 2019	13,504
Net income	$ 1,610				1,610
Other comprehensive income (loss), net of tax	94			94
Issuance of common stock	$ 218	7	211
Issuance of common stock, shares	130
Common stock options exercised, net	$ 100		100
Common stock options exercised, net, shares	20
Purchase of common stock to pay employee taxes	$ (2,269)	(2)	(2,267)
Purchase of common stock to pay employee taxes, shares	(45)
Stock-based compensation	$ 2,697		2,697
Ending balance at Mar. 31, 2020	$ 124,966	680	11,481	490	112,315
Ending balance, shares at Mar. 31, 2020	13,609
Beginning balance at Dec. 31, 2019	$ 123,326	680	10,361	1,432	110,853
Beginning balance, shares at Dec. 31, 2019	13,593
Net income	$ 1,462				1,462
Other comprehensive income (loss), net of tax	(942)			(942)
Issuance of common stock	$ 218		218
Issuance of common stock, shares	5
Common stock options exercised, net	$ 9		9
Common stock options exercised, net, shares	12
Purchase of common stock to pay employee taxes	$ (411)		(411)
Purchase of common stock to pay employee taxes, shares	(1)
Stock-based compensation	$ 1,304		1,304
Ending balance at Mar. 31, 2020	$ 124,966	680	11,481	490	112,315
Ending balance, shares at Mar. 31, 2020	13,609
Beginning balance at Sep. 30, 2020	$ 131,055	684	15,369	3,174	111,828
Beginning balance, shares at Sep. 30, 2020	13,672
Net income	$ 7,813				7,813
Other comprehensive income (loss), net of tax	57			57
Issuance of common stock	$ 296	4	292
Issuance of common stock, shares	89
Common stock options exercised, net	$ 2,240	6	2,234
Common stock options exercised, net, shares	125
Purchase of common stock to pay employee taxes	$ (2,242)	(1)	(2,241)
Purchase of common stock to pay employee taxes, shares	(18)
Stock-based compensation	$ 2,862		2,862
Ending balance at Mar. 31, 2021	$ 142,081	693	18,516	3,231	119,641
Ending balance, shares at Mar. 31, 2021	13,868
Beginning balance at Dec. 31, 2020	$ 133,407	687	16,160	5,006	111,554
Beginning balance, shares at Dec. 31, 2020	13,739
Net income	$ 8,087				8,087
Other comprehensive income (loss), net of tax	(1,775)			(1,775)
Issuance of common stock	$ 296		296
Issuance of common stock, shares	8
Common stock options exercised, net	$ 2,234	6	2,228
Common stock options exercised, net, shares	122
Purchase of common stock to pay employee taxes	$ (1,597)		(1,597)
Purchase of common stock to pay employee taxes, shares	(1)
Stock-based compensation	$ 1,429		1,429
Ending balance at Mar. 31, 2021	$ 142,081	$ 693	$ 18,516	$ 3,231	$ 119,641
Ending balance, shares at Mar. 31, 2021	13,868