Accrued Expenses and Other Current Liabilities (Product Warranty Rollforward) (Details) (USD $)	9 Months Ended
	Apr. 30, 2011	Apr. 30, 2010
Accrued Expenses and Other Current Liabilities
Product Warranty Accrual, as of the beginning of the period	$ 10,562,000	$ 14,500,000
Provision for warranty obligations	5,976,000	5,330,000
Reversal of warranty liability	(1,120,000)	(888,000)
Warranty obligation transferred with sale of certain assets and liabilities	0	(400,000)
Charges incurred	(6,572,000)	(6,677,000)
Product Warranty Accrual, as of the end of the period.	$ 8,846,000	$ 11,865,000