Share Repurchase Program (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Apr. 30, 2019	Apr. 30, 2019	Apr. 30, 2018	Jul. 31, 2018	Dec. 04, 2015	Jul. 16, 2008	Mar. 09, 2006
Accelerated Share Repurchases [Line Items]
Number of shares authorized to repurchase	7,500,000	7,500,000					3,000,000
Treasury Stock, Shares, Acquired	0	353,007	115,422
Additional number of shares authorized to repurchase					1,500,000	3,000,000
Number of shares repurchased since inception	5,905,000	5,905,000	5,552,000	5,552,000
Payments for Repurchase of Common Stock		$ 85,000	$ 25,800
Value of stock repurchased since inception	$ 357,989	$ 357,989	$ 272,989	$ 272,989
Remaining shares available for repurchase under existing program	1,595,277	1,595,277