Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2024	Nov. 05, 2024
Cover [Abstract]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2024
Document Transition Report	false
Entity File Number	1-8944
Entity Registrant Name	CLEVELAND-CLIFFS INC.
Entity Incorporation, State or Country Code	OH
Entity Tax Identification Number	34-1464672
Entity Address, Address Line One	200 Public Square,
Entity Address, City or Town	Cleveland,
Entity Address, State or Province	OH
Entity Address, Postal Zip Code	44114-2315
City Area Code	216
Local Phone Number	694-5700
Title of 12(b) Security	Common shares, par value $0.125 per share
Trading Symbol	CLF
Security Exchange Name	NYSE
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
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		493,943,553
Entity Central Index Key	0000764065
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
Amendment Flag	false