Changes in Accumulated Other Comprehensive (Loss) Income (Detail) $ in Thousands	3 Months Ended
	Oct. 31, 2017 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 460,494
Amount reclassified to earnings	(500)
Income tax benefit (provision)	(200)
Ending balance	464,634
Unrealized Losses on Available For Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(10)
Pre-tax change before reclassification to earnings	(100)
Ending balance	(100)
Unrealized Gain (Loss) on Foreign Currency Forward Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	500
Amount reclassified to earnings	(500)
Income tax benefit (provision)	100
Ending balance	100
Unrealized Gains (Losses) on Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(3,500)
Pre-tax change before reclassification to earnings	100
Income tax benefit (provision)	(100)
Ending balance	(3,500)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(2,100)
Income tax benefit (provision)	(200)
Ending balance	(2,300)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(5,100)
Ending balance	$ (5,800)