Consolidated Statements of Stockholders' Equity - USD ($) $ 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			13,398,000
Accounting Standards Update [Extensible Enumeration]		us-gaap:AccountingStandardsUpdate201409Member					us-gaap:AccountingStandardsUpdate201409Member
Net income	7,592					7,592
Other comprehensive income (loss), net of tax	(2,322)				(2,322)
Issuance of common stock	441		$ 7	434
Issuance of common stock, shares			141,000
Common stock options exercised, net	$ 282		$ 1	281
Common stock options exercised, net, shares	13,000		12,000
Purchase of common stock to pay employee taxes	$ (2,662)		$ (3)	(2,659)
Purchase of common stock to pay employee taxes, shares			(47,000)
Stock-based compensation	5,077			5,077
Ending balance at Sep. 30, 2019	122,516		$ 675	10,740	396	110,705
Ending balance, shares at Sep. 30, 2019			13,504,000
Net income	1,123					1,123
Other comprehensive income (loss), net of tax	2,778				2,778
Issuance of common stock	500		$ 8	492
Issuance of common stock, shares			149,000
Common stock options exercised, net	$ 1,115		$ 3	1,112
Common stock options exercised, net, shares	125,000		64,000
Purchase of common stock to pay employee taxes	$ (2,430)		$ (2)	(2,428)
Purchase of common stock to pay employee taxes, shares			(45,000)
Stock-based compensation	5,453			5,453
Ending balance at Sep. 30, 2020	131,055		$ 684	15,369	3,174	111,828
Ending balance, shares at Sep. 30, 2020			13,672,000
Net income	4,237					4,237
Other comprehensive income (loss), net of tax	(1,447)				(1,447)
Issuance of common stock	619		$ 5	614
Issuance of common stock, shares			100,000
Common stock options exercised, net	$ 2,509		$ 7	2,502
Common stock options exercised, net, shares	248,000		146,000
Purchase of common stock to pay employee taxes	$ (2,751)		$ (1)	(2,750)
Purchase of common stock to pay employee taxes, shares			(19,000)
Stock-based compensation	5,863			5,863
Ending balance at Sep. 30, 2021	$ 140,085		$ 695	$ 21,598	$ 1,727	$ 116,065
Ending balance, shares at Sep. 30, 2021			13,899,000