Accrued Expenses and Other Current Liabilities - Product Warranty Rollforward (Details) - USD ($)	6 Months Ended
	Jan. 31, 2016	Jan. 31, 2015
Accrued Liabilities, Current [Abstract]
Minimum coverage period of product warranty from the date of shipment	1 year
Changes in Product Warranty Liability
Accrued warranty obligations, as of the beginning of the period	$ 8,638,000	$ 8,618,000
Provision for warranty obligations	2,096,000	1,992,000
Charges incurred	(2,110,000)	(2,315,000)
Accrued warranty obligations, as of the end of the period	$ 8,624,000	$ 8,295,000