Income Taxes - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016	Jul. 31, 2016
Income Taxes [Line Items]
Discrete tax benefit		$ 1,400,000		$ 1,300,000
U.S. Federal statutory tax rate	35.00%	35.00%	35.00%	35.00%
Unrecognized tax benefits, accrued interest and penalties	$ 500,000		$ 500,000		$ 400,000
Unrecognized tax benefits, for uncertain tax positions	7,100,000		7,100,000
Maximum
Income Taxes [Line Items]
Discrete tax benefit	$ 400,000		$ 400,000