Income Taxes - Reconciliation (Details) - USD ($)	3 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Income Taxes - Income tax reconciliation
Consolidated effective income tax rate (as a percent)	27.60%	38.10%
Excess tax benefits	(8.60%)
New tax legislation	(0.70%)
Acquisition related items, net	(0.40%)
International operations	0.30%
Other	(1.10%)
Reduction of income tax expense		$ 613,000
New Accounting Pronouncement, Early Adoption, Effect | ASU 2016-09 Share-Based Payment Accounting
Income Taxes - Income tax reconciliation
Reduction of income tax expense	$ 2,241,000