Annual report [Section 13 and 15(d), not S-K Item 405]

DEBT AND CREDIT FACILITIES - Debt Issuances and Terms (Details)

v3.25.0.1
DEBT AND CREDIT FACILITIES - Debt Issuances and Terms (Details)
$ in Millions
12 Months Ended
Dec. 31, 2024
USD ($)
Days
day
Oct. 22, 2024
USD ($)
Aug. 16, 2024
USD ($)
Mar. 18, 2024
USD ($)
Dec. 31, 2023
USD ($)
Debt Instrument [Line Items]          
Total debt $ 7,148       $ 3,192
6.750% 2026 Senior Secured Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 6.75%        
Total debt $ 0       829
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 6.75%        
Total debt $ 750       750
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 100.00%        
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 103.375%        
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance          
Debt Instrument [Line Items]          
Redemption price, percentage 106.75%        
Restricted Amount (percent of original aggregate principal) 35.00%        
6.750% 2030 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three          
Debt Instrument [Line Items]          
Redemption price, percentage 101.688%        
7.000% 2027 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 7.00%        
Total debt $ 73       73
7.000% 2027 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 101.167%        
5.875% 2027 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 5.875%        
Total debt $ 556       556
5.875% 2027 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 100.979%        
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 4.625%        
Total debt $ 368       368
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 102.313%        
4.625% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three          
Debt Instrument [Line Items]          
Redemption price, percentage 101.156%        
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 4.875%        
Total debt $ 325       325
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 102.438%        
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance          
Debt Instrument [Line Items]          
Redemption price, percentage 104.875%        
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three          
Debt Instrument [Line Items]          
Redemption price, percentage 101.625%        
4.875% 2031 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Four          
Debt Instrument [Line Items]          
Redemption price, percentage 100.813%        
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 6.25%        
Total debt $ 235       235
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Minimum          
Debt Instrument [Line Items]          
Redemption notice period | day 30        
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Maximum          
Debt Instrument [Line Items]          
Redemption notice period | day 60        
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 100.00%        
6.250% 2040 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 0.40%        
Unsecured Debt | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Repurchase price if triggering event occurs 101.00%        
7.000% 2027 AK Senior Notes | AK Steel          
Debt Instrument [Line Items]          
Stated interest rate 7.00%        
Total debt $ 56       56
7.000% 2027 AK Senior Notes | AK Steel | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 101.167%        
7.000% 2032 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Stated interest rate 7.00%        
Repurchase price if triggering event occurs 101.00%        
Total debt $ 1,425   $ 600 $ 825 0
7.000% 2032 Senior Notes | Cleveland-Cliffs Inc. | Minimum          
Debt Instrument [Line Items]          
Redemption notice period | Days 10        
7.000% 2032 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 100.00%        
7.000% 2032 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 103.50%        
7.000% 2032 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance          
Debt Instrument [Line Items]          
Redemption price, percentage 107.00%        
Restricted Amount (percent of original aggregate principal) 35.00%        
7.000% 2032 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Three          
Debt Instrument [Line Items]          
Redemption price, percentage 101.75%        
6.875% 2029 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Repurchase price if triggering event occurs 10100.00%        
Total debt   $ 900     0
6.875% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 100.00%        
6.875% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 103.438%        
6.875% 2029 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance          
Debt Instrument [Line Items]          
Redemption price, percentage 106.875%        
Restricted Amount (percent of original aggregate principal) 35.00%        
7.375% 2033 Senior Notes | Cleveland-Cliffs Inc.          
Debt Instrument [Line Items]          
Repurchase price if triggering event occurs 10100.00%        
Total debt   $ 900     $ 0
7.375% 2033 Senior Notes | Cleveland-Cliffs Inc. | Minimum          
Debt Instrument [Line Items]          
Redemption notice period | Days 10        
7.375% 2033 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One          
Debt Instrument [Line Items]          
Redemption price, percentage 100.00%        
7.375% 2033 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period Two          
Debt Instrument [Line Items]          
Redemption price, percentage 103.688%        
7.375% 2033 Senior Notes | Cleveland-Cliffs Inc. | Debt Instrument, Redemption, Period One, Upon Equity Issuance          
Debt Instrument [Line Items]          
Redemption price, percentage 107.375%        
Restricted Amount (percent of original aggregate principal) 35.00%