Unaudited Consolidated Statements of Changes in Equity - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment [Member]	Common Stock	Treasury Stock	Additional Paid‑in Capital	Retained Deficit	Retained Deficit Cumulative Effect, Period of Adoption, Adjustment [Member]	Accumulated Other Comprehensive Loss	Non‑controlling Interest
Common stock issued at the beginning of the period (shares) at Sep. 30, 2019			116,008,000
Stockholders' equity, balance at the beginning of the period at Sep. 30, 2019	$ 365,822	$ (1,337)	$ 1,154	$ (2,837)	$ 552,422	$ (174,976)	$ (1,337)	$ (13,004)	$ 3,063
Treasury stock, balance at the beginning of the period (in shares) at Sep. 30, 2019				1,664,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)			3,062,000	(531,000)
Issuance of common stock, cost	15,370		$ 31		15,339
Dividends paid to non-controlling interest	(1,450)								(1,450)
Equity based compensation expense	5,984				5,984
Divestiture of Lange product line	(16,895)				(16,895)
Net income	61,416					60,957			459
Other comprehensive income (loss)	(6,407)							(6,407)
Common stock issued at the end of the period (shares) at Mar. 31, 2020			119,070,000
Stockholders' equity, balance at the end of the period at Mar. 31, 2020	422,503		$ 1,185	$ (2,837)	556,850	(115,356)		(19,411)	2,072
Treasury stock, balance at the end of the period (in shares) at Mar. 31, 2020				2,194,000
Common stock issued at the beginning of the period (shares) at Dec. 31, 2019			117,653,000
Stockholders' equity, balance at the beginning of the period at Dec. 31, 2019	415,130	$ 686	$ 1,170	$ (2,837)	543,237	(123,854)	$ 686	(4,760)	2,174
Treasury stock, balance at the beginning of the period (in shares) at Dec. 31, 2019				2,083,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)			1,417,000	111,000
Issuance of common stock, cost	11,324		$ 15		11,309
Dividends paid to non-controlling interest	(200)								(200)
Equity based compensation expense	2,304				2,304
Net income	7,910					7,812			98
Other comprehensive income (loss)	(14,651)							(14,651)
Common stock issued at the end of the period (shares) at Mar. 31, 2020			119,070,000
Stockholders' equity, balance at the end of the period at Mar. 31, 2020	$ 422,503		$ 1,185	$ (2,837)	556,850	(115,356)		(19,411)	2,072
Treasury stock, balance at the end of the period (in shares) at Mar. 31, 2020				2,194,000
Common stock issued at the beginning of the period (shares) at Sep. 30, 2020	119,486,000		119,486,000
Stockholders' equity, balance at the beginning 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 beginning of the period (in shares) at Sep. 30, 2020	2,195,000			2,195,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)			1,956,000	530,000
Issuance of common stock, cost	$ (7,101)		$ 26		(7,127)
Dividends paid to non-controlling interest	(350)								(350)
Equity based compensation expense	6,233				6,233
Net income	11,559					11,469			90
Other comprehensive income (loss)	$ 32,481
Common stock issued at the end of the period (shares) at Mar. 31, 2021	121,442,000		121,442,000
Stockholders' equity, balance at the end of the period at Mar. 31, 2021	$ 524,885		$ 1,215	$ (2,837)	564,034	(51,195)		12,009	1,659
Treasury stock, balance at the end of the period (in shares) at Mar. 31, 2021	1,664,000			1,664,000
Common stock issued at the beginning of the period (shares) at Dec. 31, 2020			120,750,000
Stockholders' equity, balance at the beginning of the period at Dec. 31, 2020	$ 501,961		$ 1,202	$ (2,837)	582,197	(56,231)		(24,083)	1,713
Treasury stock, balance at the beginning of the period (in shares) at Dec. 31, 2020				2,196,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of common stock (in shares)			692,000	(532,000)
Issuance of common stock, cost	(21,364)		$ 13		(21,377)
Dividends paid to non-controlling interest	(100)								(100)
Equity based compensation expense	3,214				3,214
Net income	5,082					5,036			46
Other comprehensive income (loss)	$ 36,092							36,092
Common stock issued at the end of the period (shares) at Mar. 31, 2021	121,442,000		121,442,000
Stockholders' equity, balance at the end of the period at Mar. 31, 2021	$ 524,885		$ 1,215	$ (2,837)	$ 564,034	$ (51,195)		$ 12,009	$ 1,659
Treasury stock, balance at the end of the period (in shares) at Mar. 31, 2021	1,664,000			1,664,000