Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Loss	Noncontrolling Interest
Beginning balance (in shares) at Sep. 30, 2018		54,585
Beginning balance at Sep. 30, 2018	$ 739,408	$ 546	$ 397,927	$ 386,622	$ (42,356)	$ (3,331)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	9,794		9,794
Release of restricted stock (in shares)		950
Release of restricted stock	10	$ 10
Taxes paid related to net share settlement of equity awards	(3,288)		(3,288)
Transfer of subsidiary shares to noncontrolling interest	0		3,195			(3,195)
Foreign currency translation loss	(10,042)				(10,042)
Deconsolidation of subsidiary	7,756					7,756
Net income (loss)	1,311			2,541		(1,230)
Ending balance (in shares) at Sep. 30, 2019		55,535
Ending balance at Sep. 30, 2019	744,949	$ 556	407,628	389,163	(52,398)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	(5,094)		(5,094)
Release of restricted stock (in shares)		711
Release of restricted stock	6	$ 6
Taxes paid related to net share settlement of equity awards	(1,435)		(1,435)
Foreign currency translation loss	(15,678)			(8)	(15,670)
Purchase and retirement of treasury shares (in shares)		(943)
Purchase and retirement of treasury stock	(5,158)	$ (11)	(2,624)	(2,523)
Net income (loss)	(68,463)			(68,463)
Ending balance (in shares) at Sep. 30, 2020		55,303
Ending balance at Sep. 30, 2020	649,127	$ 551	398,475	318,169	(68,068)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	3,946		3,946
Release of restricted stock (in shares)		508
Release of restricted stock	7	$ 7
Transfer of consideration for current period acquisition (in shares)		213
Transfer of consideration for current period acquisition	1,547	$ 2	1,545
Transfer of consideration for prior period acquisition (in shares)		33
Transfer of consideration for prior period acquisition	185		185
Taxes paid related to net share settlement of equity awards	(839)		(839)
Foreign currency translation loss	9,653				9,653
Net income (loss)	8,612			8,612
Ending balance (in shares) at Sep. 30, 2021		56,057
Ending balance at Sep. 30, 2021	$ 672,238	$ 560	$ 403,312	$ 326,781	$ (58,415)	$ 0