Leases and Other Commitments - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Oct. 31, 2017	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Leases And Other Commitments [Line Items]
Rent expense associated with the Company's operating leases		$ 1,800	$ 1,900	$ 2,300
Outstanding non-cancelable purchase orders		23,200
Restructuring charge		$ 7,167	$ 9,641	$ (354)
Vancouver Facility | Scenario, Forecast
Leases And Other Commitments [Line Items]
Restructuring charge	$ 400