Lines of Credit (Details) - USD ($) $ in Thousands	Jul. 31, 2017	Jul. 31, 2016
Line of Credit Facility [Line Items]
Outstanding cash draws, recorded as lines of credit on the accompanying consolidated balance sheets	$ 581	$ 312
Term loan	200	0
Outstanding letters of credit to support operations	2,511	2,187
Total amounts used under lines of credit	3,292	2,499
Remaining amounts available under lines of credit	36,227	36,496
Total approved unsecured lines of credit	$ 39,519	$ 38,995
Minimum [Member] | U.S. [Member]
Line of Credit Facility [Line Items]
Interest rate	3.25%
Minimum [Member] | South America [Member]
Line of Credit Facility [Line Items]
Interest rate	9.12%
Maximum [Member] | U.S. [Member]
Line of Credit Facility [Line Items]
Interest rate	3.50%
Maximum [Member] | South America [Member]
Line of Credit Facility [Line Items]
Interest rate	9.75%