Changes in Accumulated Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 531,177	$ 531,410	$ 512,580
Pre-tax change before reclassification to earnings	2,900	(4,800)	(11,500)
Amount reclassified to earnings	900	300	(500)
Income tax benefit (provision)	(400)	500	(300)
Ending balance	460,494	531,177	531,410
Unrealized Losses on Available For Sale Securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Pre-tax change before reclassification to earnings	(10)
Ending balance	(10)
Unrealized Gain (Loss) on Foreign Currency Forward Contracts
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(200)	(400)
Amount reclassified to earnings	900	300	(500)
Income tax benefit (provision)	(200)	(100)	100
Ending balance	500	(200)	(400)
Unrealized Gains (Losses) on Pension Plan
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(4,900)	(3,000)	(3,600)
Pre-tax change before reclassification to earnings	1,800	(2,600)	900
Amount reclassified to earnings		100
Income tax benefit (provision)	(400)	600	(300)
Ending balance	(3,500)	(4,900)	(3,000)
Currency Translation Adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(3,400)	(1,100)	11,400
Pre-tax change before reclassification to earnings	1,100	(2,300)	(12,400)
Income tax benefit (provision)	200		(100)
Ending balance	(2,100)	(3,400)	(1,100)
Accumulated Other Comprehensive Income (Loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	(8,460)	(4,506)	7,805
Ending balance	$ (5,139)	$ (8,460)	$ (4,506)