Income Taxes (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015
Income Tax Disclosure [Abstract]
Effective tax rate	23.00%	26.70%	25.60%	27.20%
Unrecognized tax benefits	$ 19,500,000		$ 19,500,000
Accrued interest and penalties on unrecognized tax benefits	$ 2,100,000		$ 2,100,000
Statute of limitations period, average, years			5 years
Maximum possible reduction in amount of unrecognized tax benefits			$ 1,100,000.0
Unrecognized tax benefits potential expiration period			12 months