Cover - USD ($)	11 Months Ended
	Sep. 30, 2025	Nov. 14, 2025	Apr. 30, 2025
Document Information [Line Items]
Document Type	10-KT
Document Annual Report	false
Document Transition Report	true
Document Period Start Date	Nov. 01, 2024
Document Period End Date	Sep. 30, 2025
Current Fiscal Year End Date	--09-30
Entity File Number	001-00566
Entity Registrant Name	GREIF, INC.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	31-4388903
Entity Address, Address Line One	425 Winter Road
Entity Address, City or Town	Delaware
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	43015
City Area Code	740
Local Phone Number	549-6000
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
ICFR Auditor Attestation Flag	true
Document Financial Statement Error Correction [Flag]	false
Entity Shell Company	false
Documents Incorporated by Reference	The Registrant’s Definitive Proxy Statement for use in connection with the Annual Meeting of Stockholders to be held on February 23, 2026 (the “2026 Proxy Statement”), portions of which are incorporated by reference into Parts II and III of this Form 10-KT. The 2026 Proxy Statement will be filed within 120 days of September 30, 2025.
Amendment Flag	false
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	FY
Entity Central Index Key	0000043920
Earnings per Class A common stock - basic
Document Information [Line Items]
Title of 12(b) Security	Class A Common Stock
Trading Symbol	GEF
Security Exchange Name	NYSE
Entity Public Float			$ 1,322,014,218
Entity Common Stock, Shares Outstanding		25,996,487
Earnings per Class B common stock - basic
Document Information [Line Items]
Title of 12(b) Security	Class B Common Stock
Trading Symbol	GEF.B
Security Exchange Name	NYSE
Entity Public Float			$ 259,425,578
Entity Common Stock, Shares Outstanding		21,325,535