CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Balance at Jul. 31, 2017	$ 62,971	$ 556	$ 7,457,051	$ (7,398,949)	$ 4,313
Balance, shares at Jul. 31, 2017		55,555,973
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	36,715			36,715
Preferred dividends	(1,335)			(1,335)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	8		8
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises, shares		10,462
Restricted stock grants	47	$ 52	(5)
Restricted stock grants, shares		5,225,806
Restricted stock forfeitures, shares		(49,382)
Share-based compensation	10,801		10,801
Other comprehensive items	(1,579)				(1,579)
Balance at Jul. 31, 2018	$ 107,628	$ 608	7,467,855	(7,363,569)	2,734
Balance, shares at Jul. 31, 2018	60,742,859	60,742,859
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income (loss)	$ (66,727)			(66,727)
Effect of adoption of accounting standards	6,138			6,138
Equity portion of convertible note	8,200		8,200
Preferred dividends	(2,129)			(2,129)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	15		15
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises, shares		17,454
Restricted stock grants	0	$ 10	(10)
Restricted stock grants, shares		1,045,543
Share-based compensation	1,267		1,267
Other comprehensive items	(1,700)				(1,700)
Balance at Jul. 31, 2019	$ 52,692	$ 618	$ 7,477,327	$ (7,426,287)	$ 1,034
Balance, shares at Jul. 31, 2019	61,805,856	61,805,856