Net Income Per Common Share Net Income per Common Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Mar. 05, 2020	Oct. 17, 2016	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2020	Jan. 31, 2019	Jul. 31, 2019
Anti-dilutive securities (in shares)			28,000	56,000	23,000	40,000
Common Stock, Dividends, Per Share, Cash Paid			$ 1.76	$ 1.47	$ 3.52	$ 2.94
Cash dividends declared per share			1.76	1.47	$ 3.52	$ 2.94
Payments of Dividends					$ 142,050	$ 118,714
Dividends Payable, Date to be Paid					Apr. 09, 2020
Dividends Payable, Date of Record					Mar. 26, 2020
Preferred Stock, Par or Stated Value Per Share		$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Dividends, Cash			$ 71,000	$ 59,200	$ 142,100	$ 118,700
Forecast [Member]
Cash dividends declared per share	$ 1.76
Common Stock [Member]
Stock Issued During Period, Shares, New Issues		3,327,719
Exchangeable Shares [Member]
Stock Issued During Period, Shares, New Issues		418,095