Stock Repurchase Plan (Details) (USD $) In Thousands, except Share data, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 16, 2008	Mar. 09, 2006
Payments for Repurchase of Equity [Abstract]
Number of shares authorized to repurchase				3,000,000
Additional number of shares authorized to repurchase			3,000,000
Repurchased shares	0	684,307
Number of shares repurchased since inception	4,949,111	4,949,111
Value of stock repurchased since inception	$ (193,192)	$ (193,192)
Remaining shares available for repurchase under existing program	1,050,889