Accrued Expenses and Other Current Liabilities (Product Warranty Rollforward) (Details) (USD $)	6 Months Ended
	Jan. 31, 2012	Jan. 31, 2011
Accrued Expenses and Other Current Liabilities [Abstract]
Accrued warranty obligations, as of the beginning of the period	$ 9,120,000	$ 10,562,000
Provision for warranty obligations	3,194,000	3,680,000
Reversal of warranty liability	0	(525,000)
Charges incurred	(3,462,000)	(3,986,000)
Accrued warranty obligations, as of the end of the period	$ 8,852,000	$ 9,731,000