Accrued Expenses and Other Current Liabilities (Product Warranty Rollforward) (Details) (USD $)	6 Months Ended
	Jan. 31, 2015	Jan. 31, 2014
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	$ 8,618,000	$ 7,797,000
Provision for warranty obligations	1,992,000	3,548,000
Charges incurred	(2,315,000)	(3,054,000)
Accrued warranty obligations, as of the end of the period	$ 8,295,000	$ 8,291,000