Business Segment Information (Details 1) - USD ($) $ in Thousands	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	$ 34,355	$ 36,080	$ 89,018
Total assets	443,703	399,597	518,963
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	25,797	31,400	82,706
Total assets	103,113	82,400	203,548
Foreign Countries [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Long-lived assets, net	8,558	4,680	6,312
Total assets	$ 340,590	$ 317,197	$ 315,415