Stock Repurchases (Details Textual) - shares	3 Months Ended	229 Months Ended
	Oct. 31, 2020	Oct. 31, 2020	Sep. 22, 2011
Number of stock options exercised	771,000
Stock Repurchase Program 2011
Stock Repurchase Program Additional Number Of Shares Authorized Approved			80,000,000
Stock Repurchased and Retired During Period, Shares		114,549,198
Number of shares available for repurchase under stock repurchase program	81,450,802	81,450,802
Common Stock | Stock Repurchase Program 2011
Common stock authorized for repurchase (in shares)			196,000,000