Other Accrued Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2019	Jul. 31, 2018
Other Accrued Liabilities [Abstract]
Allowance for project disallowances	$ 490	$ 687	$ 687	$ 490	$ 687
Other				896	695
Total other accrued liabilities				$ 1,386	$ 1,382
Allowance for Project Disallowances [Roll Forward]
Balance at beginning of period	687	687	1,819
Reduction of reserves recorded in prior fiscal years	(197)	0	(1,132)
Balance at end of period	$ 490	$ 687	687
Maximum [Member]
Allowance for Project Disallowances [Roll Forward]
Reduction of reserves recorded in prior fiscal years			$ 100