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, 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 income (loss)	(307)				(307)
Other comprehensive income (loss)	1,872					1,872
Employee stock purchase plan issuances (in shares)			(25)
Employee stock purchase plan issuances	334		$ 222	112
Tax withholding for share-based compensation	(1,400)
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)
Beginning balance (in shares) at Sep. 30, 2021		40,653	6,391
Beginning balance at Sep. 30, 2021	472,517	$ 407	$ (56,535)	370,699	180,692	(22,746)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	1,187				1,187
Other comprehensive income (loss)	(212)					(212)
Employee stock purchase plan issuances (in shares)			(18)
Employee stock purchase plan issuances	321		$ 161	160
Tax withholding for share-based compensation	(6,025)		$ (1,726)	(4,299)
Taxes paid for net share settlement of share-based payment awards (in shares)			74
Issuance of stock under stock award plans (in shares)		760
Issuance of stock under stock award plans	4,227	$ 7		4,220
Stock-based compensation expense	2,017			2,017
Ending balance (in shares) at Dec. 31, 2021		41,413	6,447
Ending balance at Dec. 31, 2021	$ 474,032	$ 414	$ (58,100)	$ 372,797	$ 181,879	$ (22,958)