Restructuring Accrual Activity (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017
Restructuring Cost and Reserve [Line Items]
Beginning Balance			$ 86	$ 876
Accretion				216
Additions to expense	$ 550	$ 299	685	406
Cash paid			(506)	(1,057)
Ending Balance	265	441	265	441
Restructuring Charges
Restructuring Cost and Reserve [Line Items]
Additions to expense			685	406
Severance Costs
Restructuring Cost and Reserve [Line Items]
Beginning Balance			21	142
Cash paid			(308)	(165)
Ending Balance	55	220	55	220
Severance Costs | Restructuring Charges
Restructuring Cost and Reserve [Line Items]
Additions to expense			342	243
Facility Lease
Restructuring Cost and Reserve [Line Items]
Beginning Balance			65	734
Accretion				216
Cash paid			(198)	(892)
Ending Balance	$ 210	$ 221	210	221
Facility Lease | Restructuring Charges
Restructuring Cost and Reserve [Line Items]
Additions to expense			$ 343	$ 163