Recent Accounting Pronouncements (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Recent Accounting Pronouncements
Reduction of income tax expense		$ 661,000		$ 1,274,000
ASU 2016-09 Share-Based Payment Accounting
Recent Accounting Pronouncements
Reduction of income tax expense			$ 2,286,000
ASU 2016-09 Share-Based Payment Accounting | New Accounting Pronouncement, Early Adoption, Effect
Recent Accounting Pronouncements
Reduction of income tax expense	$ 45,000		$ 2,286,000