Acquisition-Related Restructuring Plan - Activity of Facility Related Exit Costs (Details) - USD ($)	3 Months Ended		9 Months Ended		117 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018
Restructuring Reserve [Roll Forward]
Present value of estimated facility-related exit costs, beginning balance			$ 1,941,000		$ 2,100,000
Cash payments made			(1,214,000)		(11,802,000)
Cash payments received					8,600,000
Accreted interest recorded	$ 19,000	$ 44,000	76,000	$ 151,000	1,905,000
Liability recorded as of period end as accrued expenses and other current liabilities in the Condensed Consolidated Balance Sheet	$ 803,000		$ 803,000		$ 803,000