Document and Entity Information - shares	3 Months Ended
	Oct. 27, 2018	Apr. 30, 2019
Document Information [Line Items]
Entity Registrant Name	ECOLOGY & ENVIRONMENT INC
Entity Central Index Key	0000809933
Current Fiscal Year End Date	--07-31
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Ex Transition Period	false
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Oct. 27, 2018
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q1
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,110,130
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,205,005