Stock Repurchase Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018	Dec. 04, 2015	Jul. 16, 2008	Mar. 09, 2006
Accelerated Share Repurchases [Line Items]
Treasury Stock, Shares, Acquired	256,418	353,007	115,422
Repurchases of Common Stock	$ 46,422	$ 85,000	$ 25,800
Number of shares authorized to repurchase	7,500,000					3,000,000
Additional number of shares authorized to repurchase				1,500,000	3,000,000
Number of shares repurchased since inception	6,161,141	5,905,000
Value of stock repurchased since inception	$ 404,411	$ 357,989
Remaining shares available for repurchase under existing program	1,338,859