Acquisition-Related Restructuring Plan - Activity of Facility Related Exit Costs (Details) - USD ($)	3 Months Ended		111 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Oct. 31, 2017
Restructuring Reserve [Roll Forward]
Present value of estimated facility-related exit costs, beginning balance	$ 1,941,000		$ 2,100,000
Cash payments made	(397,000)		(10,985,000)
Cash payments received			8,600,000
Accreted interest recorded	32,000	$ 56,000	1,861,000
Present value of estimated facility-related exit costs, ending balance	$ 1,576,000		$ 1,576,000