Restatement of Unaudited Condensed Consolidated Financial Statements, Condensed Consolidated Statements of Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
Oct. 27, 2018	Oct. 28, 2017
Consolidated Statements of Comprehensive Income [Abstract]
Net (loss) income including noncontrolling interests	$ (115)	$ 688
Foreign currency translation adjustments	(127)	(14)
Unrealized investment (losses) gains, net	0	(3)
Comprehensive (loss) income	(242)	671
Comprehensive (income) loss attributable to noncontrolling interests	55	(94)
Comprehensive (loss) income attributable to Ecology and Environment Inc.	$ (187)	577
As Previously Reported [Member]
Consolidated Statements of Comprehensive Income [Abstract]
Net (loss) income including noncontrolling interests		648
Foreign currency translation adjustments		29
Unrealized investment (losses) gains, net		(3)
Comprehensive (loss) income		674
Comprehensive (income) loss attributable to noncontrolling interests		(129)
Comprehensive (loss) income attributable to Ecology and Environment Inc.		545
GAC Deconsolidation Adjustments [Member]
Consolidated Statements of Comprehensive Income [Abstract]
Net (loss) income including noncontrolling interests		(15)
Foreign currency translation adjustments		(43)
Unrealized investment (losses) gains, net		0
Comprehensive (loss) income		(58)
Comprehensive (income) loss attributable to noncontrolling interests		35
Comprehensive (loss) income attributable to Ecology and Environment Inc.		(23)
Out of Period Adjustments [Member]
Consolidated Statements of Comprehensive Income [Abstract]
Net (loss) income including noncontrolling interests		55
Foreign currency translation adjustments		0
Unrealized investment (losses) gains, net		0
Comprehensive (loss) income		55
Comprehensive (income) loss attributable to noncontrolling interests		0
Comprehensive (loss) income attributable to Ecology and Environment Inc.		$ 55

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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