Changes in Accumulated Other Comprehensive (Loss) Income (Detail) $ in Thousands	6 Months Ended
	Jan. 31, 2018 USD ($)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 460,494
Pre-tax change before reclassification to earnings	5,000
Amount reclassified to earnings	(200)
Income tax benefit (provision)	(200)
Ending balance	477,341
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	(200)
Income tax benefit (provision)	100
Ending balance	400
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)
Pre-tax change before reclassification to earnings	5,000
Income tax benefit (provision)	(200)
Ending balance	2,700
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(5,100)
Ending balance	$ (500)