Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Revision of Prior Period Change in Accounting Principle Adjustment [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Retained Earnings [Member]	Retained Earnings [Member] Revision of Prior Period Change in Accounting Principle Adjustment [Member]
Beginning balance at Sep. 30, 2018	$ 108,610	$ 5,498	$ 670	$ 7,607	$ 2,718	$ 97,615	$ 5,498
Beginning balance, shares at Sep. 30, 2018			13,398
Net income	4,038					4,038
Other comprehensive income (loss), net of tax	(741)				(741)
Issuance of common stock	210		$ 7	203
Issuance of common stock, shares			135
Common stock options exercised, net	67			67
Common stock options exercised, net, shares			3
Purchase of common stock to pay employee taxes	(2,559)		$ (2)	(2,557)
Purchase of common stock to pay employee taxes, shares			(46)
Stock-based compensation	3,509			3,509
Ending balance at Jun. 30, 2019	118,632		$ 675	8,829	1,977	107,151
Ending balance, shares at Jun. 30, 2019			13,490
Beginning balance at Mar. 31, 2019	115,313		$ 674	7,510	1,444	105,685
Beginning balance, shares at Mar. 31, 2019			13,489
Net income	1,466					1,466
Other comprehensive income (loss), net of tax	533				533
Issuance of common stock	1		$ 1
Issuance of common stock, shares			1
Common stock options exercised, net	12			12
Common stock options exercised, net, shares			1
Purchase of common stock to pay employee taxes	(12)			(12)
Purchase of common stock to pay employee taxes, shares			(1)
Stock-based compensation	1,319			1,319
Ending balance at Jun. 30, 2019	118,632		$ 675	8,829	1,977	107,151
Ending balance, shares at Jun. 30, 2019			13,490
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	4,069					4,069
Other comprehensive income (loss), net of tax	1,073				1,073
Issuance of common stock	218		$ 7	211
Issuance of common stock, shares			133
Common stock options exercised, net	951		$ 2	949
Common stock options exercised, net, shares			53
Purchase of common stock to pay employee taxes	(2,281)		$ (2)	(2,279)
Purchase of common stock to pay employee taxes, shares			(45)
Stock-based compensation	4,037			4,037
Ending balance at Jun. 30, 2020	130,583		$ 682	13,658	1,469	114,774
Ending balance, shares at Jun. 30, 2020			13,645
Beginning balance at Mar. 31, 2020	124,966		$ 680	11,481	490	112,315
Beginning balance, shares at Mar. 31, 2020			13,609
Net income	2,459					2,459
Other comprehensive income (loss), net of tax	979				979
Issuance of common stock, shares			3
Common stock options exercised, net	851		$ 2	849
Common stock options exercised, net, shares			33
Purchase of common stock to pay employee taxes	(12)			(12)
Stock-based compensation	1,340			1,340
Ending balance at Jun. 30, 2020	$ 130,583		$ 682	$ 13,658	$ 1,469	$ 114,774
Ending balance, shares at Jun. 30, 2020			13,645