Accrued Expenses and Other Current Liabilities (Product Warranty Rollforward) (Details) (USD $)	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
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	$ 7,797,000	$ 7,883,000
Provision for warranty obligations	1,983,000	2,237,000
Charges incurred	(1,845,000)	(1,610,000)
Accrued warranty obligations, as of the end of the period	$ 7,935,000	$ 8,510,000