CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Total	Current Acquisition	Prior Acquisition	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Common Stock Current Acquisition	Common Stock Prior Acquisition	Additional Paid-in Capital	Additional Paid-in Capital Current Acquisition	Additional Paid-in Capital Prior Acquisition	Additional Paid-in Capital Cumulative Effect, Period of Adoption, Adjustment	Retained Earnings	Retained Earnings Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Loss
Accounting Standards Update [Extensible Enumeration]	Accounting Standards Update 2020-06
Beginning balance (in shares) at Sep. 30, 2020					55,303
Beginning balance at Sep. 30, 2020	$ 649,127				$ 551			$ 398,475				$ 318,169		$ (68,068)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	3,946							3,946
Transfer of consideration for current period acquisition (in shares)						213	33
Transfer of equity consideration for acquisition		$ 1,547	$ 185			$ 2			$ 1,545	$ 185
Release of restricted stock (in shares)					508
Release of restricted stock	7				$ 7
Taxes paid related to net share settlement of equity awards	(839)							(839)
Foreign currency translation adjustment, net of income tax expense for our investment in unconsolidated affiliate of $666, $229 and $280 for the years ended September 30, 2023, 2022 and 2021, respectively	9,653											0		9,653
Net income	8,612											8,612
Ending balance (in shares) at Sep. 30, 2021					56,057
Ending balance at Sep. 30, 2021	672,238			$ (36,638)	$ 560			403,312			$ (62,804)	326,781	$ 26,166	(58,415)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	5,053							5,053
Transfer of consideration for other investment (in shares)					213
Transfer of consideration for other investment	1,500				$ 2			1,498
Release of restricted stock (in shares)					393
Release of restricted stock	4				$ 4
Taxes paid related to net share settlement of equity awards	(792)							(792)
Foreign currency translation adjustment, net of income tax expense for our investment in unconsolidated affiliate of $666, $229 and $280 for the years ended September 30, 2023, 2022 and 2021, respectively	2,746													2,746
Purchase and retirement of treasury shares (in shares)					(238)
Purchase and retirement of treasury stock	(2,040)				$ (2)			(937)				(1,101)
Net income	50,160											50,160
Ending balance (in shares) at Sep. 30, 2022					56,425
Ending balance at Sep. 30, 2022	692,231				$ 564			345,330				402,006		(55,669)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	9,539							9,539
Transfer of consideration for current period acquisition (in shares)					10
Transfer of equity consideration for acquisition	99							99
Release of restricted stock (in shares)					373
Release of restricted stock	5				$ 5
Taxes paid related to net share settlement of equity awards (in shares)					(1)
Taxes paid related to net share settlement of equity awards	(1,148)							(1,148)
Foreign currency translation adjustment, net of income tax expense for our investment in unconsolidated affiliate of $666, $229 and $280 for the years ended September 30, 2023, 2022 and 2021, respectively	23,567													23,567
Purchase and retirement of treasury shares (in shares)					(1,967)
Purchase and retirement of treasury stock	(16,988)				$ (20)			(7,639)				(9,329)
Net income	38,463											38,463
Ending balance (in shares) at Sep. 30, 2023					54,840
Ending balance at Sep. 30, 2023	$ 745,768				$ 549			$ 346,181				$ 431,140		$ (32,102)