Accrued Expenses and Other Current Liabilities (Product Warranty Rollforward) (Details) (USD $)	3 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Accrued Liabilities, Current [Abstract]
Accrued warranty obligations, as of the beginning of the period	$ 7,883,000	$ 9,120,000
Provision for warranty obligations	2,237,000	1,624,000
Charges incurred	(1,610,000)	(1,461,000)
Accrued warranty obligations, as of the end of the period	$ 8,510,000	$ 9,283,000
Minimum coverage period of product warranty from the date of shipment	1 year