Property, Plant and Equipment (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Jul. 31, 2016
Property, Plant and Equipment [Abstract]
Equipment	$ 75,867	$ 73,856
Land and buildings	62,255	60,452
Computer software	88,480	68,607
Leasehold improvements	1,977	1,710
Furniture and fixtures	1,474	1,428
Property, plant and equipment, gross	230,053	206,053
Less accumulated depreciation and amortization	(141,059)	(118,719)
Property, plant and equipment, net	$ 88,994	$ 87,334