Contract Receivables, net, Disaggregation of Revenues (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Disaggregation of Revenue [Abstract]
Gross revenue	$ 88,510	$ 90,684	$ 96,083
U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	70,622	71,735	80,542
South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	17,888	18,949	15,541
Time and Materials [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	40,505	38,562	47,732
Time and Materials [Member] | U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	40,478	38,562	47,732
Time and Materials [Member] | South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	27	0	0
Fixed Price [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	30,974	33,262	31,773
Fixed Price [Member] | U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	13,113	14,313	16,232
Fixed Price [Member] | South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	17,861	18,949	15,541
Cost-Plus [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	17,031	18,860	16,578
Cost-Plus [Member] | U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	17,031	18,860	16,578
Cost-Plus [Member] | South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	$ 0	$ 0	$ 0