Goodwill and Intangible Assets - Additional Information (Detail) - USD ($)		12 Months Ended
	Dec. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Goodwill and Intangible Assets Disclosure [Line Items]
Goodwill		$ 73,915,000	$ 57,450,000
Acquisition of goodwill		16,400,000
Goodwill expected to be deductible for tax purposes		10,500,000	4,000,000
Amortization expense related to acquired finite-lived intangible assets		8,400,000	8,900,000	$ 7,800,000
Impairment of goodwill	$ 0
Trade names
Goodwill and Intangible Assets Disclosure [Line Items]
Indefinite lived intangible assets		$ 7,600,000	$ 7,600,000
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