Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)		3 Months Ended
	Dec. 31, 2015	Oct. 31, 2016	Oct. 31, 2015	Jul. 31, 2016
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill		$ 73,915,000		$ 73,915,000
Indefinite lived intangible assets		7,600,000		$ 7,600,000
Amortization expense related to acquired intangible assets		$ 2,000,000	$ 2,000,000
Impairment of goodwill	$ 0
Impairment of intangible assets	$ 0
Minimum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives		1 year
Maximum
Goodwill and Intangible Assets Disclosure [Line Items]
Intangible assets, estimated useful lives		14 years