Quarterly report pursuant to Section 13 or 15(d)

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details)

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BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Details) - Stelco Holdings Inc
Nov. 01, 2024
USD ($)
shares
Jul. 12, 2024
USD ($)
Nov. 01, 2024
$ / shares
Business Acquisition [Line Items]      
Expected enterprise value of acquisition   $ 2,500,000,000  
Subsequent Event      
Business Acquisition [Line Items]      
Shares of Cliffs common shares issued to Stelco Holdings stockholders (in shares) | shares 0.454    
Expected enterprise value of acquisition $ 3,200,000,000    
Stelco Holdings Inc | Subsequent Event      
Business Acquisition [Line Items]      
Price per share (in dollars per share) | $ / shares     $ 60.00