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, 2019	Mar. 27, 2019	Mar. 07, 2019	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018	Jul. 31, 2018
Anti-dilutive securities (in shares)				56,000	5,000	40,000	5,000
Income Tax Expense (Benefit)				$ 63,973	$ 3,594	$ 27,568	$ (89,810)
Common Stock, Dividends, Per Share, Cash Paid				$ 1.47	$ 1.05	$ 2.940	$ 2.11
Cash dividends declared per share				$ 1.47	$ 1.053	$ 2.940	$ 2.106
Payments of Dividends				$ 59,170	$ 42,600	$ 118,714	$ 85,226
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			$ 1.76
Dividends Payable, Date to be Paid	Apr. 11, 2019
Dividends Payable, Date of Record		Mar. 27, 2019
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