Commitments and Contingencies - Additional Information (Detail) - USD ($)	9 Months Ended	12 Months Ended
	Jul. 31, 2018	Oct. 31, 2017
Loss Contingencies [Line Items]
Contingent liability under purchase agreements for future chassis inventory purchases	$ 42,000,000	$ 85,900,000
Repurchase agreement	2 years
Represents the gross value of all vehicles under repurchase agreements	$ 288,500,000	288,500,000
Maximum [Member]
Loss Contingencies [Line Items]
Estimated loss exposure under contract	$ 21,400,000	$ 600,000