STOCKHOLDERS' EQUITY - Changes in stockholders' equity (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Issued	61,810,253,000		61,805,856,000
Beginning balance (shares)	61,805,856,000
Beginning balance	$ 52,692	$ 107,628
Net income	4,792	(7,365)
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	2	6
Restricted stock grants		0
Share-based compensation	176	792
Other comprehensive items	$ 11	(1,232)
Ending balance (shares)	61,810,253,000
Ending balance	$ 57,137	$ 105,431
Common Stock
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common Stock, Shares, Issued	61,810,253,000	61,386,888,000	61,805,856,000	60,742,859,000
Beginning balance	$ 618	$ 608
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises (in shares)	4,397,000	3,107,000
Restricted stock grants (in shares)		640,922,000
Restricted stock grants		$ 6
Ending balance	$ 618	614
Additional Paid-in Capital
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	7,477,327	7,467,855
Issuance of common stock pursuant to employee stock purchase plan and stock option exercises	2	6
Restricted stock grants		(6)
Share-based compensation	176	792
Ending balance	7,477,505	7,468,647
Accumulated Deficit
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	(7,426,287)	(7,363,569)
Net income	4,792	(7,365)
Ending balance	(7,422,031)	(7,365,332)
Accumulated Other Comprehensive Income
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Beginning balance	1,034	2,734
Other comprehensive items	11	(1,232)
Ending balance	$ 1,045	$ 1,502