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 (shares) at Sep. 30, 2017		54,398
Beginning Balance at Sep. 30, 2017	$ 659,926	$ 544	$ 348,532	$ 351,666	$ (38,367)	$ (2,449)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	2,889		2,889
Release of restricted stock (shares)		66
Release of restricted stock	1	$ 1
Taxes paid related to net share settlement of equity awards	(311)		(311)
Foreign currency translation loss, net	(6,575)				(6,535)	(40)
Net income (loss)	12,133			12,748		(615)
Ending balance (shares) at Dec. 31, 2017		54,464
Ending Balance at Dec. 31, 2017	668,063	$ 545	351,110	364,414	(44,902)	(3,104)
Beginning balance (shares) at Sep. 30, 2018		54,585
Beginning Balance at Sep. 30, 2018	744,706	$ 546	397,927	392,180	(42,616)	(3,331)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock compensation	2,247		2,247
Release of restricted stock (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 loss, net	(6,488)				(6,488)
Net income (loss)	(4,721)			(4,244)		(477)
Ending balance (shares) at Dec. 31, 2018		55,445
Ending Balance at Dec. 31, 2018	$ 732,464	$ 554	$ 400,081	$ 387,936	$ (49,104)	$ (7,003)