CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive Income
Beginning balance (in shares) at Jul. 31, 2017		55,555,973
Beginning balance at Jul. 31, 2017	$ 62,971	$ 556	$ 7,457,051	$ (7,398,949)	$ 4,313
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	44,248			44,248
Preferred dividends	(799)			(799)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)		6,703
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	3		3
Restricted stock grants (in shares)		5,225,806
Restricted stock grants	47	$ 52
Restricted stock forfeitures (in shares)		(49,382)
Restricted stock forfeitures	0
Share-based compensation	9,657		9,657
Other comprehensive items	2,531				2,531
Ending balance (in shares) at Apr. 30, 2018		60,739,100
Ending balance at Apr. 30, 2018	118,658	$ 608	7,466,706	(7,355,500)	6,844
Beginning balance at Jan. 31, 2018	128,697	$ 603	7,464,451	(7,344,638)	8,281
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(10,333)			(10,333)
Preferred dividends	(529)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)		4,258
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	0		0
Restricted stock grants (in shares)		528,896
Restricted stock grants		$ 5	(5)
Share-based compensation	2,260		2,260
Other comprehensive items	(1,437)				(1,437)
Ending balance (in shares) at Apr. 30, 2018		60,739,100
Ending balance at Apr. 30, 2018	$ 118,658	$ 608	7,466,706	(7,355,500)	6,844
Beginning balance (in shares) at Jul. 31, 2018	60,742,859	60,742,859
Beginning balance at Jul. 31, 2018	$ 107,628	$ 608	7,467,855	(7,363,569)	2,734
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(28,745)			(28,745)
Effect of adoption of accounting standards	6,138			6,138
Equity portion of convertible note	8,200		8,200
Preferred dividends	(1,598)			(1,598)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)		13,794
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	15		15
Restricted stock grants (in shares)		1,045,543
Restricted stock grants		$ 10	(10)
Share-based compensation	1,174		1,174
Other comprehensive items	$ (426)				(426)
Ending balance (in shares) at Apr. 30, 2019	61,802,196	61,802,196
Ending balance at Apr. 30, 2019	$ 92,386	$ 618	7,477,234	(7,387,774)	2,308
Beginning balance at Jan. 31, 2019	94,537	$ 618	7,468,628	(7,377,622)	2,913
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(9,627)			(9,627)
Equity portion of convertible note	8,200		8,200
Preferred dividends	(525)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)		4,389
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	2		2
Share-based compensation	404		404
Other comprehensive items	$ (605)				(605)
Ending balance (in shares) at Apr. 30, 2019	61,802,196	61,802,196
Ending balance at Apr. 30, 2019	$ 92,386	$ 618	$ 7,477,234	$ (7,387,774)	$ 2,308