Consolidated Statement of Shareholders' 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, 2017	$ 111,557		$ 655	$ 5,413	$ 3,417	$ 102,072
Beginning balance, shares at Sep. 30, 2017			13,095,000
Net income (loss)	(4,457)					(4,457)
Other comprehensive income (loss), net of tax	(699)				(699)
Issuance of common stock	340		$ 7	333
Issuance of common stock, shares			137,000
Common stock options exercised, net	$ 1,749		$ 22	1,727
Common stock options exercised, net, shares	450,000		440,000
Purchase of common stock to pay employee taxes	$ (4,687)		$ (14)	(4,673)
Purchase of common stock to pay employee taxes, shares			(274,000)
Stock-based compensation	4,807			4,807
Ending balance at Sep. 30, 2018	108,610	$ 5,498	$ 670	7,607	2,718	97,615	$ 5,498
Ending balance, shares at Sep. 30, 2018			13,398,000
Accounting Standards Update [Extensible List]		us-gaap:AccountingStandardsUpdate201409Member					us-gaap:AccountingStandardsUpdate201409Member
Net income (loss)	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 (loss)	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