Acquisition-Related Restructuring Plan - Activity of Facility Related Exit Costs (Details) - USD ($)	3 Months Ended		6 Months Ended		114 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018
Restructuring Reserve [Roll Forward]
Present value of estimated facility-related exit costs, beginning balance			$ 1,941,000		$ 2,100,000
Cash payments made			(805,000)		(11,393,000)
Cash payments received					8,600,000
Accreted interest recorded	$ 25,000	$ 51,000	57,000	$ 107,000	1,886,000
Liability recorded as of period end as accrued expenses and other current liabilities in the Condensed Consolidated Balance Sheet	$ 1,193,000		$ 1,193,000		$ 1,193,000