Stock-Based Compensation Expense and Shareholders' Equity (Details Textual) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018	Sep. 14, 2011
Class of Stock [Line Items]
Share price (in dollars per share)	$ 117.66	$ 102.08	$ 86.20
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common Stock, Shares, Issued (in shares)	83,461,925	82,140,883
Common stock, shares outstanding (in shares)	83,461,925	82,140,883
Stock Plan 2011
Class of Stock [Line Items]
Number of shares authorized				7,500,000
Maximum increase in percentage of outstanding number of shares of the Company's common stock (as a percent)	5.00%
Performance Shares
Class of Stock [Line Items]
Period of time based vesting	4 years
TSR PSUs
Class of Stock [Line Items]
Period of time based vesting	3 years
Restricted stock units RSUs
Class of Stock [Line Items]
Period of time based vesting	4 years
Share based compensation expense, performance based awards	$ 13.1	$ 19.1	$ 9.4