Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Sep. 30, 2019		34,608	6,367
Beginning balance at Sep. 30, 2019	$ 348,978	$ 346	$ (54,339)	$ 266,567	$ 161,919	$ (25,515)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	208				208
Other comprehensive income	2,660					2,660
Employee stock purchase plan issuances (in shares)			(25)
Employee stock purchase plan issuances	286		$ 214	72
Taxes paid for net share settlement of share-based payment awards (in shares)			89
Taxes paid for net share settlement of share-based payment awards	(1,577)		$ (1,577)
Issuance of stock under stock award plans (in shares)		618
Issuance of stock under stock award plans	4,160	$ 6		4,154
Stock-based compensation expense	1,600			1,600
Ending balance (in shares) at Dec. 31, 2019		35,226	6,431
Ending balance at Dec. 31, 2019	356,315	$ 352	$ (55,702)	272,393	162,127	(22,855)
Beginning balance (in shares) at Sep. 30, 2020		35,513	6,353
Beginning balance at Sep. 30, 2020	371,500	$ 355	$ (55,109)	279,741	170,330	(23,817)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net (loss) income	(307)				(307)
Other comprehensive income	1,872					1,872
Employee stock purchase plan issuances (in shares)			(25)
Employee stock purchase plan issuances	334		$ 222	112
Taxes paid for net share settlement of share-based payment awards (in shares)			84
Taxes paid for net share settlement of share-based payment awards	(1,446)		$ (1,446)
Issuance of stock under stock award plans (in shares)		577
Issuance of stock under stock award plans	3,944	$ 6		3,938
Stock-based compensation expense	1,745			1,745
Ending balance (in shares) at Dec. 31, 2020		36,090	6,412
Ending balance at Dec. 31, 2020	$ 377,642	$ 361	$ (56,333)	$ 285,536	$ 170,023	$ (21,945)