Intangible Assets and Goodwill - Additional Information (Detail) - USD ($) $ in Thousands	6 Months Ended	9 Months Ended
	Jan. 31, 2016	Apr. 30, 2017	Jul. 31, 2016
Intangible Assets And Goodwill [Line Items]
Goodwill		$ 377,693	$ 377,693
Pre-tax, non-cash goodwill impairment charge	$ 9,113	0
Towables
Intangible Assets And Goodwill [Line Items]
Goodwill		334,822	334,822
Other
Intangible Assets And Goodwill [Line Items]
Goodwill		$ 42,871	$ 42,871