CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income	Cumulative Effect, Period of Adoption, Adjustment [Member]	Cumulative Effect, Period of Adoption, Adjustment [Member] Accumulated Deficit
Balance at Jul. 31, 2018	$ 107,628	$ 608	$ 7,467,855	$ (7,363,569)	$ 2,734	$ 6,138	$ 6,138
Balance (in shares) at Jul. 31, 2018		60,742,859
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(66,727)			(66,727)
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	15		15
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)		17,454
Restricted stock grants		$ 10	(10)
Restricted stock grants (in 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 (in shares) at Jul. 31, 2019	60,742,859	61,805,856
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	$ (5,284)			(5,284)
Preferred dividends	(2,129)			(2,129)
Issuance of common stock pursuant to employee stock purchase plan	10		10
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)		21,540
Restricted stock grants, net of forfeitures		$ 10	(10)
Restricted stock grants, net of forfeitures (in shares)		960,523
Share-based compensation	720		720
Other comprehensive items	2,809				2,809
Balance at Jul. 31, 2020	$ 48,818	$ 628	$ 7,478,047	$ (7,433,700)	$ 3,843
Balance (in shares) at Jul. 31, 2020	62,787,919