Accrued Expenses and Other Current Liabilities (Product Warranty Rollforward) (Details) (USD $)	12 Months Ended
	Jul. 31, 2011	Jul. 31, 2010
Accrued Expenses and Other Current Liabilities [Abstract]
Accrued warranty obligations, as of the beginning of the period	$ 10,562,000	$ 14,500,000
Provision for warranty obligations	8,203,000	6,786,000
Reversal of warranty liability	(1,120,000)	(1,685,000)
Warranty obligation transferred with sale of certain assets and liabilities	0	(400,000)
Charges incurred	(8,525,000)	(8,639,000)
Accrued warranty obligations, as of the end of the period	$ 9,120,000	$ 10,562,000