Long - Term Debt - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Oct. 31, 2017	Oct. 31, 2016	Jul. 31, 2016	Jul. 31, 2017
Line of Credit Facility [Line Items]
Line of credit, outstanding amount	$ 90,000			$ 145,000
Interest expense	1,412	$ 2,560
Fees to secure the facility, amortized amount	$ 393	$ 393
Asset-based revolving credit facility
Line of Credit Facility [Line Items]
Line of credit, maturity period	5 years
Line of credit, commencement date	Jun. 30, 2016
Line of credit, maturity date	Jun. 30, 2021
Line of credit, outstanding amount	$ 90,000			145,000
Line of credit, borrowing availability	$ 407,675
Weighted-average interest rate on borrowings	2.57%	2.11%
Fees to secure the facility, amount incurred			$ 7,850
Fees to secure the facility, unamortized amount	$ 5,756			$ 6,149
Asset-based revolving credit facility | Interest expense
Line of Credit Facility [Line Items]
Fees to secure the facility, amortized amount	$ 393	$ 393
Asset-based revolving credit facility | Maximum
Line of Credit Facility [Line Items]
Fees to secure the facility, amortization period	5 years
Asset-based revolving credit facility | LIBOR and base rate
Line of Credit Facility [Line Items]
Interest expense	$ 611	$ 1,878