Business Segment Information (Details 3) - USD ($) $ in Thousands	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	$ 88,994	$ 87,374	$ 91,316
Total assets	518,963	469,658	485,682
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	82,682	82,060	86,750
Total assets	203,548	257,385	277,342
Foreign Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	6,312	5,314	4,566
Total assets	$ 315,415	$ 212,273	$ 208,340