Variable Interest Entities and Equity Method Investment, Equity Method Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity investment carrying value at beginning of period	$ 1,463
GAC net income attributable to EEI	595	$ 368	$ 363
Equity investment carrying value at end of period	$ 2,058	$ 1,463
GAC [Member]
Equity Method Investment [Abstract]
Ownership percentage	55.10%	55.10%
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity investment carrying value at beginning of period	$ 1,463	$ 1,944	1,793
GAC net income attributable to EEI	595	368	363
EEI's portion of dividends declared by GAC	0	(849)	(212)
Equity investment carrying value at end of period	2,058	1,463	1,944
Equity Method Investment, Summarized Financial Information [Abstract]
Current assets	5,713	4,383
Noncurrent assets	501	167
Total assets	6,214	4,550
Current liabilities	2,620	2,643
Noncurrent liabilities	593	10
Total liabilities	3,213	2,653
Total Ecology and Environment Inc. shareholder's equity	1,678	1,175
Noncontrolling interests shareholders' equity	1,323	722
Total shareholders' equity	3,001	1,897
Total liabilities and shareholders' equity	6,214	4,550
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Gross revenue	11,987	7,737	7,530
Direct cost of services and subcontract costs	(7,286)	(4,633)	(4,632)
Income from operations	1,381	568	727
Net income	1,079	668	659
Net income attributable to EEI	$ 595	$ 368	$ 363