Variable Interest Entities and Equity Method Investment, Equity Method Investment (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity investment carrying value at beginning of period	$ 2,058
GAC net income attributable to EEI	346	$ 595	$ 368
Equity investment carrying value at end of period	$ 1,658	$ 2,058
GAC [Member]
Equity Method Investment [Abstract]
Ownership percentage	52.48%	55.10%
Equity Method Investment, Financial Statement, Reported Amounts [Abstract]
Equity investment carrying value at beginning of period	$ 2,058	$ 1,463	1,944
GAC net income attributable to EEI	346	595	368
EEI's portion of other comprehensive loss recorded by GAC	(414)	0	0
Gain on dilution of investment in GAC	(17)	0	0
EEI's portion of dividends declared by GAC	(349)	0	(849)
Equity investment carrying value at end of period	1,658	2,058	1,463
Equity Method Investment, Summarized Financial Information [Abstract]
Current assets	5,671	5,713
Noncurrent assets	1,215	501
Total assets	6,886	6,214
Current liabilities	3,232	2,620
Noncurrent liabilities	847	593
Total liabilities	4,079	3,213
Total Ecology and Environment Inc. shareholder's equity	1,806	1,678
Noncontrolling interest in shareholders' equity	1,001	1,323
Total shareholders' equity	2,807	3,001
Total liabilities and shareholders' equity	6,886	6,214
Equity Method Investment, Summarized Financial Information, Income Statement [Abstract]
Gross revenue	12,912	11,987	7,737
Direct cost of services and subcontract costs	(8,353)	(7,286)	(4,633)
Income from operations	924	1,381	568
Net income	637	1,079	668
Net income attributable to EEI	$ 346	$ 595	$ 368