Property, Plant, and Equipment (Detail) (USD $) In Thousands, unless otherwise specified			12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012 Building And Improvement Minimum	Jul. 31, 2012 Building And Improvement Maximum	Jul. 31, 2012 Leasehold and Capital Lease Improvements	Jul. 31, 2012 Manufacturing and Engineering Equipment Minimum	Jul. 31, 2012 Manufacturing and Engineering Equipment Maximum	Jul. 31, 2012 Furniture, Fixtures and Computer Equipment Minimum	Jul. 31, 2012 Furniture, Fixtures and Computer Equipment Maximum	Jul. 31, 2012 Motor Vehicles Minimum	Jul. 31, 2012 Motor Vehicles Maximum
Property, Plant and Equipment [Line Items]
Property, plant and equipment estimated useful lives			35 years	40 years		4 years	7 years	3 years	7 years	3 years	5 years
Property, plant and equipment estimated useful lives					lesser of useful life or the lease term
Property, plant, and equipment:
Land and land improvements	$ 7,209	$ 6,457
Building and improvements	74,954	58,276
Leasehold and capital lease improvements	11,147	11,371
Manufacturing and engineering equipment	82,380	80,261
Furniture, fixtures, and computer equipment	17,478	16,119
Motor vehicles	1,405	1,872
Property, Plant and Equipment, Gross, Total	194,573	174,356
Less accumulated depreciation and amortization	(97,804)	(91,199)
Property, plant, and equipment, net	$ 96,769	$ 83,157