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	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	2,247		2,247
Release of restricted stock (in shares)		860
Release of restricted stock	8	$ 8
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 gain (loss)	(6,383)				(6,383)
Net income (loss)	(3,843)			(3,366)		(477)
Ending balance (in shares) at Dec. 31, 2018		55,445
Ending Balance at Dec. 31, 2018	728,149	$ 554	400,081	383,256	(48,739)	(7,003)
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]
Foreign currency translation gain (loss)	(5,570)
Net income (loss)	1,956
Ending balance (in shares) at Jun. 30, 2019		55,445
Ending Balance at Jun. 30, 2019	747,316	$ 554	404,880	389,808	(47,926)	0
Beginning balance (in shares) at Dec. 31, 2018		55,445
Beginning Balance at Dec. 31, 2018	728,149	$ 554	400,081	383,256	(48,739)	(7,003)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	2,424		2,424
Deconsolidation of subsidiary	7,756					7,756
Foreign currency translation gain (loss)	(1,211)				(1,211)
Net income (loss)	2,641			3,394		(753)
Ending balance (in shares) at Mar. 31, 2019		55,445
Ending Balance at Mar. 31, 2019	739,759	$ 554	402,505	386,650	(49,950)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	2,375		2,375
Foreign currency translation gain (loss)	2,024				2,024
Net income (loss)	3,158			3,158
Ending balance (in shares) at Jun. 30, 2019		55,445
Ending Balance at Jun. 30, 2019	747,316	$ 554	404,880	389,808	(47,926)	$ 0
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]
Foreign currency translation gain (loss)	(18,359)
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 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
Net income (loss)	(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)