Significant Transactions During the Fiscal Year Ended July 31, 2019 (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended	12 Months Ended
	Aug. 28, 2019	Jul. 31, 2019	Jul. 31, 2019	Jul. 31, 2018
Class A [Member]
Agreement and Plan of Merger [Abstract]
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01	$ 0.01
Class B [Member]
Agreement and Plan of Merger [Abstract]
Common stock, par value (in dollars per share)		$ 0.01	$ 0.01	$ 0.01
Selling, General and Administrative Expenses [Member] | U.S. Operations [Member]
Staff Reduction Programs [Abstract]
Employee severance and termination costs			$ 1,000
Expenses Associated with Restatements of Financial Statements [Abstract]
Incremental audit, tax and legal expenses			$ 1,000
Merger Agreement [Member]
Agreement and Plan of Merger [Abstract]
Expenses related to merger agreement		$ 300
Subsequent Event [Member] | Merger Agreement [Member]
Agreement and Plan of Merger [Abstract]
Minimum amount of merger expenses considered for special dividend	$ 3,050
Termination fee	$ 4,000
Subsequent Event [Member] | Merger Agreement [Member] | Class A [Member]
Agreement and Plan of Merger [Abstract]
Common stock, par value (in dollars per share)	$ 0.01
Common stock, conversion into cash (in dollars per share)	15.00
Subsequent Event [Member] | Merger Agreement [Member] | Class B [Member]
Agreement and Plan of Merger [Abstract]
Common stock, par value (in dollars per share)	0.01
Common stock, conversion into cash (in dollars per share)	15.00
Subsequent Event [Member] | Merger Agreement [Member] | Maximum [Member]
Agreement and Plan of Merger [Abstract]
Special dividend payable (in dollars per share)	$ 0.50
Reimbursement of expenses	$ 1,750