Document and Entity Information - USD ($)	12 Months Ended
	Jul. 31, 2017	Sep. 29, 2017	Jan. 31, 2017
Document Information [Line Items]
Entity Registrant Name	ECOLOGY & ENVIRONMENT INC
Entity Central Index Key	0000809933
Current Fiscal Year End Date	--07-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Smaller Reporting Company
Entity Public Float			$ 29,925,693
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	FY
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jul. 31, 2017
Common Class A [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		3,008,458
Common Class B [Member]
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		1,293,146