Share Repurchase Program (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended	9 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Jan. 31, 2019	Apr. 30, 2020	Apr. 30, 2019	Jul. 31, 2019	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	160,800	0		256,418	353,007
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		6,161,141	5,905,000	5,905,000
Payments for Repurchase of Common Stock	$ 25,000		$ 85,000	$ 46,422	$ 85,000
Value of stock repurchased since inception	$ 404,411	$ 357,989		$ 404,411	$ 357,989	$ 357,989
Remaining shares available for repurchase under existing program	1,338,859			1,338,859