Stockholder's Investments - Schedule of Other Activity in Stockholders' Investments (Details) - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Class of Stock [Line Items]
Sale Of Shares At Cost	$ 41	$ 40	$ (90)
Purchase Of Shares At Cost	(610)	(839)	(815)
Ending Balance, Other Stockholders Equity	0	(3,863)	(3,064)	$ (2,159)
Shares Held Rabbi Trust At Cost [Member]
Class of Stock [Line Items]
Sale Of Shares At Cost	1,288	1,278	2,235
Purchase Of Shares At Cost	(925)	(1,017)	(1,035)
Ending Balance, Other Stockholders Equity	$ (8,124)	$ (8,487)	$ (8,748)	$ (9,948)
Ending Balance, Other Stockholders Equity Shares	314,082	347,081	362	423
Deferred Compensation [Member]
Class of Stock [Line Items]
Sale Of Shares At Cost	$ (1,247)	$ (1,238)	$ (2,325)
Purchase Of Shares At Cost	315	178	220
Ending Balance, Other Stockholders Equity	$ 8,124	$ 4,624	$ 5,684	$ 7,789
Ending Balance, Other Stockholders Equity Shares	314,082	201,418	252	339