Property, Plant and Equipment - Schedule of Property, Plant and Equipment (Detail) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2014	Jul. 31, 2013
Property Plant And Equipment [Abstract]
Equipment	$ 438,899	$ 436,127
Land and buildings	53,895	51,294
Computer software	116,775	105,449
Leasehold improvements	42,190	45,141
Furniture and fixtures	6,249	6,187
Property, plant and equipment, gross	658,008	644,198
Less accumulated depreciation and amortization	(576,248)	(563,456)
Property, plant and equipment, net	$ 81,760	$ 80,742