Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)		3 Months Ended		6 Months Ended
	Dec. 31, 2015	Jan. 31, 2016	Jan. 31, 2015	Jan. 31, 2016	Jan. 31, 2015	Jul. 31, 2015
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill		$ 73,791,000		$ 73,791,000		$ 57,450,000
Acquisition of goodwill				16,300,000
Indefinite lived intangible assets		7,600,000		7,600,000		$ 7,600,000
Amortization expense related to acquired intangible assets		$ 2,000,000	$ 2,200,000	$ 4,000,000	$ 4,400,000
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