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, 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)		(5,506)			$ (1,881)	$ (5,506)
Other comprehensive loss, net of tax			(6,298)			$ (6,298)
Stock issued under equity incentive plans (in shares)						151
Stock issued under employee stock purchase plans, value	710
Stock issued under employee stock purchase plans (in shares)						14
Purchase of common stock, value	(2,355)
Purchase of common stock (in shares)						(53)
Stock- based compensation	5,260
Cash dividends paid		(3,676)
Balance at Jun. 30, 2018	41,465	785,303	(112,924)	(36,078)	(1,881)
Balance (in shares) at Jun. 30, 2018						27,239
Balance at Mar. 31, 2018	40,079	779,012	(103,438)	(36,078)
Balance (in shares) at Mar. 31, 2018						27,225
Increase (Decrease) in Stockholders' Equity
Net income (loss)		6,291			(1,881)	$ 6,291
Other comprehensive loss, net of tax			(9,486)			$ (9,486)
Stock issued under employee stock purchase plans (in shares)						19
Purchase of common stock, value	(114)
Purchase of common stock (in shares)						(5)
Stock- based compensation	1,500
Balance at Jun. 30, 2018	41,465	785,303	(112,924)	(36,078)	(1,881)
Balance (in shares) at Jun. 30, 2018						27,239
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)		7,931			(8,970)	$ 7,931
Other comprehensive loss, net of tax			(1,827)			$ (1,827)
Stock issued under equity incentive plans (in shares)						144
Stock issued under employee stock purchase plans, value	783
Stock issued under employee stock purchase plans (in shares)						15
Purchase of common stock, value	(3,419)
Purchase of common stock (in shares)						(49)
Stock- based compensation	10,760
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		(4,205)
Other	1	2			9
Balance at Jun. 30, 2019	268,965	825,396	(112,470)	(36,078)	19,769	$ 965,582
Balance (in shares) at Jun. 30, 2019						31,160
Balance at Mar. 31, 2019	264,612	801,486	(110,156)	(36,078)	23,325
Balance (in shares) at Mar. 31, 2019						31,150
Increase (Decrease) in Stockholders' Equity
Net income (loss)		23,910			(3,566)	$ 23,910
Other comprehensive loss, net of tax			(2,314)			$ (2,314)
Stock issued under equity incentive plans (in shares)						12
Purchase of common stock (in shares)						(2)
Stock- based compensation	4,402
Other	(49)				10
Balance at Jun. 30, 2019	$ 268,965	$ 825,396	$ (112,470)	$ (36,078)	$ 19,769	$ 965,582
Balance (in shares) at Jun. 30, 2019						31,160