Stock-Based Compensation - Taxes (Details) - USD ($)	3 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Stock-based awards, additional disclosure
Deduction in income tax due to exercise of options and vesting of restricted stock (in dollars)	$ 5,376,000	$ 3,041,000
Income tax deductions previously recorded in income tax expense over the equity awards' vesting period	3,135,000	1,552,000
Increase in additional paid-in capital due to excess tax benefit on stock-based compensation expense (in dollars)		1,489,000
Reduction of income tax expense		$ 613,000
New Accounting Pronouncement, Early Adoption, Effect | ASU 2016-09 Share-Based Payment Accounting
Stock-based awards, additional disclosure
Reduction of income tax expense	$ 2,241,000