Stockholder's Investments - Schedule of Other Activity in Stockholders' Investments (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Class of Stock [Line Items]
Sale Of Shares At Cost	$ 0	$ 41	$ 40
Purchase Of Shares At Cost	0	(610)	(839)
Ending Balance, Other Stockholders Equity	0	0	(3,863)	$ (3,064)
Shares Held Rabbi Trust At Cost [Member]
Class of Stock [Line Items]
Sale Of Shares At Cost	977	1,288	1,278
Purchase Of Shares At Cost	(1,075)	(925)	(1,017)
Ending Balance, Other Stockholders Equity	$ (8,222)	$ (8,124)	$ (8,487)	$ (8,748)
Ending Balance, Other Stockholders Equity Shares	299,916	314,082	347,081	362,025
Deferred Compensation [Member]
Class of Stock [Line Items]
Sale Of Shares At Cost	$ (977)	$ (1,247)	$ (1,238)
Purchase Of Shares At Cost	1,075	315	178
Ending Balance, Other Stockholders Equity	$ 8,222	$ 8,124	$ 4,624	$ 5,684
Ending Balance, Other Stockholders Equity Shares	299,916	314,082	201,418	252,261