CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock	Retained Earnings	Accumulated Other Comprehensive Loss	Treasury Stock	Noncontrolling Interest in VIE	Total
Balance at Sep. 30, 2016	$ 32,756	$ 813,035	$ (119,817)	$ (36,078)
Balance (in shares) at Sep. 30, 2016						26,992
Increase (Decrease) in Stockholders' Equity
Net income (loss)		(11,209)				$ (11,209)
Other comprehensive income (loss), net of tax			13,191			$ 13,191
Stock issued under equity incentive plans (in shares)						158
Stock issued under employee stock purchase plans, value	2,234
Stock issued under employee stock purchase plans (in shares)						32
Purchase of common stock, value	(2,444)
Purchase of common stock (in shares)						(55)
Stock- based compensation	5,269
Tax expense from equity incentive plans	35
Cash dividends paid		(7,341)
Balance at Sep. 30, 2017	37,850	794,485	(106,626)	(36,078)
Balance (in shares) at Sep. 30, 2017						27,127
Increase (Decrease) in Stockholders' Equity
Net income (loss)		12,310			$ (274)	$ 12,310
Other comprehensive income (loss), net of tax			(1,623)			$ (1,623)
Stock issued under equity incentive plans (in shares)						158
Stock issued under employee stock purchase plans, value	1,517
Stock issued under employee stock purchase plans (in shares)						26
Purchase of common stock, value	(2,449)
Purchase of common stock (in shares)						(56)
Stock- based compensation	8,090
Equity contribution of noncontrolling interest					24,349
Cumulative effect of accounting standard adoption		2,394	(2,394)
Cash dividends paid		(7,355)
Balance at Sep. 30, 2018	45,008	801,834	(110,643)	(36,078)	24,075	$ 724,196
Balance (in shares) at Sep. 30, 2018						27,255
Increase (Decrease) in Stockholders' Equity
Net income (loss)		49,694			(9,811)	$ 49,694
Other comprehensive income (loss), net of tax			(29,050)			$ (29,050)
Stock issued under equity incentive plans (in shares)						145
Stock issued under employee stock purchase plans, value	1,832
Stock issued under employee stock purchase plans (in shares)						32
Purchase of common stock, value	(3,688)
Purchase of common stock (in shares)						(49)
Stock- based compensation	15,488
Cumulative effect of accounting standard adoption		19,834			4,655
Stock issued under equity offering, net, value	215,832
Stock issued under equity offering, net (in shares)						3,795
Cash dividends paid		(8,414)
Balance at Sep. 30, 2019	$ 274,472	$ 862,948	$ (139,693)	$ (36,078)	$ 18,919	$ 980,568
Balance (in shares) at Sep. 30, 2019						31,178