Quarterly report [Sections 13 or 15(d)]

ACQUISITIONS - Consideration (Details)

v3.25.3
ACQUISITIONS - Consideration (Details)
$ / shares in Units, $ / shares in Units, $ in Millions, $ in Millions
Nov. 01, 2024
USD ($)
shares
Nov. 01, 2024
CAD ($)
$ / shares
shares
Sep. 30, 2025
shares
Dec. 31, 2024
shares
Nov. 01, 2024
USD ($)
$ / shares
shares
Business Combination [Line Items]          
Common shares, outstanding (in shares)     494,699,774 493,948,905  
Stelco Holdings Inc          
Business Combination [Line Items]          
Payments to Acquire Businesses, Gross $ 2,450 $ 3,418      
Business Combination, Consideration Transferred, Equity Interest, Fair Value Method 343 343      
Business Combination, Consideration Transferred, Debt Consideration | $         $ 415
Business Combination, Consideration Transferred | $ $ 3,208        
Common shares, outstanding (in shares)         54,448,388
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number         2,516,415
Total consideration shares         56,964,803
Price per share (in dollars per share) | (per share)   $ 60.00     $ 13.27
Foreign Currency Exchange Rate, Translation         0.7168
Business Acquisition, Shares Exchange Ratio 0.454 0.454      
Shares of Cliffs common shares issued to Stelco Holdings stockholders (in shares) 25,862,021 25,862,021