Intangible Assets and Goodwill - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended
	Apr. 30, 2016	Jan. 31, 2016	Apr. 30, 2016	Jul. 31, 2015
Intangible Assets And Goodwill [Line Items]
Goodwill	$ 303,509		$ 303,509	$ 312,622
Pre-tax, non-cash goodwill impairment charge	0	$ 9,113	9,113
Towables
Intangible Assets And Goodwill [Line Items]
Goodwill	260,638		260,638	269,751
Other
Intangible Assets And Goodwill [Line Items]
Goodwill	$ 42,871		$ 42,871	$ 42,871