Cover Page - shares	9 Months Ended
	Jul. 31, 2019	Aug. 26, 2019
Document Information [Line Items]
Document Quarterly Report	true
Entity Incorporation, State or Country Code	DE
Entity Address, Address Line One	425 Winter Road
Document Transition Report	false
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jul. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	Q3
Entity Registrant Name	GREIF INC
Entity Central Index Key	0000043920
Current Fiscal Year End Date	--10-31
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Address, City or Town	Delaware
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	43015
Entity File Number	001-00566
City Area Code	740
Local Phone Number	549-6000
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Tax Identification Number	31-4388903
Entity Shell Company	false
Class A Common Stock
Document Information [Line Items]
Title of 12(b) Security	Class A Common Stock
Trading Symbol	GEF
Entity Common Stock, Shares Outstanding		26,257,943
Security Exchange Name	NYSE
Class B Common Stock
Document Information [Line Items]
Title of 12(b) Security	Class B Common Stock
Trading Symbol	GEF-B
Entity Common Stock, Shares Outstanding		22,007,725
Security Exchange Name	NYSE