Income Taxes (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Income Tax Disclosure [Abstract]
Effective tax rate	29.80%	23.00%	28.40%	25.60%
Unrecognized tax benefits	$ 17,800,000		$ 17,800,000
Accrued interest and penalties on unrecognized tax benefits	$ 2,000,000		$ 2,000,000
Statute of limitations period, average, years			5 years
Maximum possible reduction in amount of unrecognized tax benefits			$ 1,300,000.0
Unrecognized tax benefits potential expiration period			12 months