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. 09, 2017	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Anti-dilutive securities (in shares)		2,000	19,000	1,000	10,000
Cash dividends declared per share		$ 0.8100	$ 0.6225	$ 1.6200	$ 1.2450
Payments of Dividends		$ 32,400	$ 22,600	$ 61,772	$ 45,221
Dividends Payable, Date to be Paid		Apr. 13, 2017
Dividends Payable, Date of Record		Mar. 29, 2017
Scenario, Forecast [Member]
Cash dividends declared per share	$ 1.0530
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