Supplemental Cash Flow Information (Details) - USD ($)	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Supplemental Cash Flow Information
Interest paid	$ 3,001,000	$ 1,970,000	$ 1,787,000
Income tax payments	$ 33,559,000	$ 25,239,000	$ 20,481,000