Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Beginning Balance (in shares) at Sep. 30, 2019		55,535
Beginning Balance at Sep. 30, 2019	$ 744,949	$ 556	$ 407,628	$ 389,163	$ (52,398)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	1,695		1,695
Release of restricted stock (in shares)		463
Release of restricted stock	5	$ 5
Taxes paid related to net share settlement of equity awards	(1,395)		(1,395)
Foreign currency translation gain (loss)	6,071				6,071
Purchase and retirement of treasury stock (in shares)		(142)
Purchase and retirement of treasury stock	(963)	$ (2)	(488)	(473)
Net income (loss)	1,238			1,238
Ending Balance (in shares) at Dec. 31, 2019		55,856
Ending Balance at Dec. 31, 2019	751,600	$ 559	407,440	389,928	(46,327)
Beginning Balance (in shares) at Sep. 30, 2019		55,535
Beginning Balance at Sep. 30, 2019	744,949	$ 556	407,628	389,163	(52,398)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	(45,123)
Ending Balance (in shares) at Jun. 30, 2020		55,068
Ending Balance at Jun. 30, 2020	679,912	$ 551	408,601	341,517	(70,757)
Beginning Balance (in shares) at Sep. 30, 2019		55,535
Beginning Balance at Sep. 30, 2019	744,949	$ 556	407,628	389,163	(52,398)
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)
Beginning Balance (in shares) at Dec. 31, 2019		55,856
Beginning Balance at Dec. 31, 2019	751,600	$ 559	407,440	389,928	(46,327)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	930		930
Release of restricted stock (in shares)		13
Release of restricted stock	1	$ 1
Taxes paid related to net share settlement of equity awards	(63)		(63)
Foreign currency translation gain (loss)	(29,846)				(29,846)
Purchase and retirement of treasury stock (in shares)		(801)
Purchase and retirement of treasury stock	(4,195)	$ (9)	(2,136)	(2,050)
Net income (loss)	(40,874)			(40,874)
Ending Balance (in shares) at Mar. 31, 2020		55,068
Ending Balance at Mar. 31, 2020	677,553	$ 551	406,171	347,004	(76,173)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	2,430		2,430
Foreign currency translation gain (loss)	5,416				5,416
Net income (loss)	(5,487)			(5,487)
Ending Balance (in shares) at Jun. 30, 2020		55,068
Ending Balance at Jun. 30, 2020	679,912	$ 551	408,601	341,517	(70,757)
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	524		524
Release of restricted stock (in shares)		296
Release of restricted stock	5	$ 5
Taxes paid related to net share settlement of equity awards	(730)		(730)
Foreign currency translation gain (loss)	11,277				11,277
Net income (loss)	4,299			4,299
Ending Balance (in shares) at Dec. 31, 2020		55,599
Ending Balance at Dec. 31, 2020	664,502	$ 556	398,269	322,468	(56,791)
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]
Net income (loss)	7,059
Ending Balance (in shares) at Jun. 30, 2021		56,057
Ending Balance at Jun. 30, 2021	673,218	$ 560	402,522	325,228	(55,092)
Beginning Balance (in shares) at Dec. 31, 2020		55,599
Beginning Balance at Dec. 31, 2020	664,502	$ 556	398,269	322,468	(56,791)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	1,094		1,094
Transfer of consideration for prior period acquisition (in shares)		33
Transfer of consideration for prior period acquisition	185		185
Release of restricted stock (in shares)		212
Release of restricted stock	2	$ 2
Taxes paid related to net share settlement of equity awards	(109)		(109)
Foreign currency translation gain (loss)	(1,760)				(1,760)
Net income (loss)	5,330			5,330
Ending Balance (in shares) at Mar. 31, 2021		55,844
Ending Balance at Mar. 31, 2021	669,244	$ 558	399,439	327,798	(58,551)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	1,538		1,538
Transfer of consideration for current period acquisition (in shares)		213
Transfer of consideration for current period acquisition	1,547	$ 2	1,545
Foreign currency translation gain (loss)	3,459				3,459
Net income (loss)	(2,570)			(2,570)
Ending Balance (in shares) at Jun. 30, 2021		56,057
Ending Balance at Jun. 30, 2021	$ 673,218	$ 560	$ 402,522	$ 325,228	$ (55,092)