Condensed Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid‑in Capital	Retained Deficit	Accumulated Other Comprehensive Loss	Non‑controlling Interest	Cumulative Effect, Period of Adoption, Adjustment [Member] Retained Deficit
Common stock issued at the beginning of the period (shares) at Sep. 30, 2017		105,359,000
Stockholders' equity, balance at the beginning of the period at Sep. 30, 2017	$ 216,575	$ 1,054	$ (2,607)	$ 388,986	$ (170,006)	$ (5,989)	$ 5,137
Treasury stock, balance at the beginning of the period (shares) at Sep. 30, 2017			410,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Equity based compensation expense	15,742			15,742
Issuance of common stock (shares)		8,333,000
Shares withheld related to net share settlement (including tax withholdings)		$ 83
Adjustments To Additional Paid In Capital, Capital Contribution	137,605			137,522
Stock repurchases (shares)			18,000
Stock repurchases	(230)		$ (230)
Dividends paid to non‑controlling interest	(3,725)						(3,725)
Net income (loss)	7,884				6,135		1,749
Shares withheld related to net share settlement (including tax withholdings) (shares)		1,324,000	659,000
Shares withheld related to net share settlement (including tax withholdings)	(8,807)	$ 8		(8,815)
Common stock issued at the end of the period (shares) at Sep. 30, 2018		115,016,000
Stockholders' equity, balance at the end of the period at Sep. 30, 2018	362,016	$ 1,145	$ (2,837)	533,435	(163,871)	(9,017)	3,161	$ (1,582)
Treasury stock, balance at the end of the period (shares) at Sep. 30, 2018			1,087,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	(3,028)
Equity based compensation expense	19,903			19,903
Issuance of common stock (shares)		108,000
Shares withheld related to net share settlement (including tax withholdings)	363	$ 0		363
Dividends paid to non‑controlling interest	(1,150)						(1,150)
Net income (loss)	(8,471)				(9,523)		1,052
Shares withheld related to net share settlement (including tax withholdings) (shares)		884,000	577,000
Shares withheld related to net share settlement (including tax withholdings)	$ (1,270)	$ 9		(1,279)
Common stock issued at the end of the period (shares) at Sep. 30, 2019	116,008,000	116,008,000
Stockholders' equity, balance at the end of the period at Sep. 30, 2019	$ 365,822	$ 1,154	$ (2,837)	552,422	(174,976)	(13,004)	3,063	$ (1,337)
Treasury stock, balance at the end of the period (shares) at Sep. 30, 2019	1,664,000		1,664,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	$ (3,987)
Equity based compensation expense	10,509			10,509
Issuance of common stock (shares)		3,478,000	531,000
Shares withheld related to net share settlement (including tax withholdings)	18,927	$ 35		18,892
Dividends paid to non‑controlling interest	(1,890)						(1,890)
Divestiture of Memcor product line	(16,895)			(16,895)
Net income (loss)	$ 114,395				113,649
Common stock issued at the end of the period (shares) at Sep. 30, 2020	119,486,000	119,486,000
Stockholders' equity, balance at the end of the period at Sep. 30, 2020	$ 482,063	$ 1,189	$ (2,837)	$ 564,928	$ (62,664)	$ (20,472)	$ 1,919
Treasury stock, balance at the end of the period (shares) at Sep. 30, 2020	2,195,000		2,195,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other Comprehensive Income (Loss), Net of Tax	$ (7,468)