CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Treasury Stock	Accumulated Other Comprehensive Income/(Loss)
Beginning balance (in shares) at Sep. 30, 2018		12,281			(806)
Beginning balance at Sep. 30, 2018	$ 301,644	$ 123	$ 56,769	$ 291,530	$ (24,999)	$ (21,779)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	9,890			9,890
Foreign currency translation adjustments	(2,743)					(2,743)
Stock-based compensation (in shares)		92
Stock-based compensation	3,839	$ 1	3,838
Shares withheld in lieu of employee tax withholding	(1,454)		(1,454)
Dividends paid	(11,998)			(11,998)
Postretirement benefit adjustment, net of tax	(25)					(25)
Ending balance (in shares) at Sep. 30, 2019		12,373			(806)
Ending balance at Sep. 30, 2019	299,153	$ 124	59,153	289,422	$ (24,999)	(24,547)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	16,660			16,660
Foreign currency translation adjustments	60					60
Stock-based compensation (in shares)		49
Stock-based compensation	3,474	$ 0	3,474
Shares withheld in lieu of employee tax withholding	(629)		(629)
Dividends paid	(12,066)			(12,066)
Postretirement benefit adjustment, net of tax	(26)					(26)
Ending balance (in shares) at Sep. 30, 2020		12,422			(806)
Ending balance at Sep. 30, 2020	306,626	$ 124	61,998	294,016	$ (24,999)	(24,513)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	631			631
Foreign currency translation adjustments	4,253					4,253
Stock-based compensation (in shares)		76
Stock-based compensation	2,583	$ 1	2,582
Shares withheld in lieu of employee tax withholding	(632)		(632)
Dividends paid	(12,142)			(12,142)
Postretirement benefit adjustment, net of tax	(96)					(96)
Ending balance (in shares) at Sep. 30, 2021		12,498			(806)
Ending balance at Sep. 30, 2021	$ 301,223	$ 125	$ 63,948	$ 282,505	$ (24,999)	$ (20,356)