CONDENSED 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, 2018	$ 45,008	$ 801,834	$ (110,643)	$ (36,078)	$ 24,075
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 income (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)
Share - 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
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 income (loss), net of tax			(2,314)			$ (2,314)
Stock issued under equity incentive plans (in shares)						12
Purchase of common stock (in shares)						(2)
Share - based compensation	4,402
Other	(49)				10
Balance at Jun. 30, 2019	268,965	825,396	(112,470)	(36,078)	19,769
Balance (in shares) at Jun. 30, 2019						31,160
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
Increase (Decrease) in Stockholders' Equity
Net income (loss)		(60,853)			181	$ (60,853)
Other comprehensive income (loss), net of tax			(15,664)			$ (15,664)
Stock issued under equity incentive plans (in shares)						156
Stock issued under employee stock purchase plans, value	1,169
Stock issued under employee stock purchase plans (in shares)						19
Purchase of common stock, value	(3,660)
Purchase of common stock (in shares)						(54)
Share - based compensation	15,271
Equity contribution of noncontrolling interest					1,892
Cumulative effect of accounting standard adoption		(824)
Cash dividends paid		(4,225)
Balance at Jun. 30, 2020	287,252	797,046	(155,357)	(36,078)	20,992	$ 913,855
Balance (in shares) at Jun. 30, 2020						31,299
Balance at Mar. 31, 2020	281,840	798,201	(148,159)	(36,078)	9,731
Balance (in shares) at Mar. 31, 2020						31,296
Increase (Decrease) in Stockholders' Equity
Net income (loss)		(1,155)			9,369	$ (1,155)
Other comprehensive income (loss), net of tax			(7,198)			$ (7,198)
Stock issued under equity incentive plans (in shares)						3
Share - based compensation	5,412
Equity contribution of noncontrolling interest					1,892
Balance at Jun. 30, 2020	$ 287,252	$ 797,046	$ (155,357)	$ (36,078)	$ 20,992	$ 913,855
Balance (in shares) at Jun. 30, 2020						31,299