Revenue and Contract Receivables, net, Disaggregation of Revenues (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 26, 2019	Jan. 27, 2018	Jan. 26, 2019	Jan. 27, 2018
Disaggregation of Revenue [Abstract]
Gross revenue	$ 20,252	$ 21,289	$ 42,004	$ 47,394
U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	19,161	16,384	37,171	37,219
South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	1,091	4,905	4,833	10,175
Time and Materials [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	9,732	8,837	18,988	18,788
Time and Materials [Member] | U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	9,732	8,837	18,988	18,788
Time and Materials [Member] | South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	0	0	0	0
Fixed Price [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	6,894	7,663	14,247	17,263
Fixed Price [Member] | U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	5,803	2,758	9,415	7,088
Fixed Price [Member] | South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	1,091	4,905	4,832	10,175
Cost-Plus [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	3,626	4,789	8,769	11,343
Cost-Plus [Member] | U.S. Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	3,626	4,789	8,768	11,343
Cost-Plus [Member] | South American Operations [Member]
Disaggregation of Revenue [Abstract]
Gross revenue	$ 0	$ 0	$ 1	$ 0