Property, Plant, and Equipment (Detail) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Property, Plant and Equipment [Line Items]
Land and improvements	$ 7,100	$ 7,000
Building and improvements	86,400	85,000
Leasehold improvements	9,800	10,100
Equipment and software	147,200	142,700
Furniture and fixtures	7,200	7,600
Demonstration Inventory	9,900	3,900
Property, Plant and Equipment, Gross, Total	267,600	256,300
Less accumulated depreciation and amortization	(164,900)	(148,500)
Total property, plant and equipment	$ 102,676	$ 107,790	$ 106,300
Land and Improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	15 years
Building and Improvement | Minimum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	10 years
Building and Improvement | Maximum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	35 years
Leasehold and Capital Lease Improvements
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives	lesser of useful life or the lease term
Equipment and Software | Minimum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	3 years
Equipment and Software | Maximum
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	7 years
Furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	5 years
Demonstration Inventory
Property, Plant and Equipment [Line Items]
Property, plant, and equipment, Estimated Useful Lives (Years)	3 years