Property, Plant, and Equipment (Detail) (USD $)			3 Months Ended
	Oct. 31, 2013	Jul. 31, 2013	Oct. 31, 2013 Building And Improvement Minimum	Oct. 31, 2013 Building And Improvement Maximum	Oct. 31, 2013 Leasehold and Capital Lease Improvements	Oct. 31, 2013 Manufacturing and Engineering Equipment Minimum	Oct. 31, 2013 Manufacturing and Engineering Equipment Maximum	Oct. 31, 2013 Furniture, Fixtures and Computer Equipment Minimum	Oct. 31, 2013 Furniture, Fixtures and Computer Equipment Maximum	Oct. 31, 2013 Motor Vehicles Minimum	Oct. 31, 2013 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
Land and land improvements	$ 7,500,000	$ 7,400,000
Building and improvements	83,800,000	83,000,000
Leasehold and capital lease improvements	10,700,000	10,700,000
Manufacturing and engineering equipment	96,300,000	103,400,000
Furniture, fixtures, and computer equipment	33,400,000	22,900,000
Motor vehicles	2,000,000	2,000,000
Property, Plant and Equipment, Gross, Total	233,700,000	229,400,000
Less accumulated depreciation and amortization	(122,000,000)	(118,400,000)
Total property, plant and equipment, net	$ 111,725,000	$ 110,983,000