Net Income Per Common Share Net Income per Common Share (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands			3 Months Ended		6 Months Ended
	Apr. 11, 2018	Mar. 27, 2018	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Jul. 31, 2017
Anti-dilutive securities (in shares)			5,000	2,000	5,000	1,000
Cash dividends declared per share			$ 1.053	$ 0.810	$ 2.106	$ 1.620
Payments of Dividends			$ 42,600	$ 32,400	$ 85,226	$ 61,772
Preferred Stock, Par or Stated Value Per Share			$ 0.01	$ 0.01	$ 0.01	$ 0.01	$ 0.01
Scenario, Forecast [Member]
Cash dividends declared per share	$ 1.470
Dividends Payable, Date to be Paid	Apr. 11, 2018
Dividends Payable, Date of Record		Mar. 27, 2018
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