Quarterly report pursuant to Section 13 or 15(d)

DEBT AND CREDIT FACILITIES - Schedule Of Long-Term Debt (Details)

v3.20.2
DEBT AND CREDIT FACILITIES - Schedule Of Long-Term Debt (Details) - USD ($)
$ in Millions
Sep. 30, 2020
Dec. 31, 2019
Debt Instrument [Line Items]    
Long-term Debt, Gross $ 4,490.7  
LONG-TERM DEBT 4,309.8 $ 2,113.8
Credit Facility    
Debt Instrument [Line Items]    
Long-term Line of Credit $ 400.0  
Cleveland-Cliffs Inc. [Member] | 4.875% 2024 Senior Secured Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 5.00% 5.00%
Long-term Debt, Gross $ 394.5 $ 400.0
Unamortized Debt Issuance Expense (3.7) (4.6)
Debt Instrument, Unamortized Discount (1.5) (1.8)
Long-term Debt $ 389.3 $ 393.6
Cleveland-Cliffs Inc. [Member] | 9.875% 2025 Senior Secured Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 10.57%  
Long-term Debt, Gross $ 955.2  
Unamortized Debt Issuance Expense (8.1)  
Debt Instrument, Unamortized Discount (25.8)  
Long-term Debt $ 921.3  
Cleveland-Cliffs Inc. [Member] | 6.75% 2026 Senior Secured Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 6.99%  
Long-term Debt, Gross $ 845.0  
Unamortized Debt Issuance Expense (21.4)  
Debt Instrument, Unamortized Discount (9.0)  
Long-term Debt $ 814.6  
Cleveland-Cliffs Inc. [Member] | 6.375% 2025 Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 8.11%  
Long-term Debt, Gross $ 64.3  
Unamortized Debt Issuance Expense (0.2)  
Debt Instrument, Unamortized Discount (4.6)  
Long-term Debt $ 59.5  
Cleveland-Cliffs Inc. [Member] | 1.50% 2025 Convertible Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 6.26% 6.26%
Long-term Debt, Gross $ 296.3 $ 316.3
Unamortized Debt Issuance Expense (3.7) (4.6)
Debt Instrument, Unamortized Discount (53.0) (65.0)
Long-term Debt $ 239.6 $ 246.7
Cleveland-Cliffs Inc. [Member] | 5.75% 2025 Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 6.01% 6.01%
Long-term Debt, Gross $ 396.2 $ 473.3
Unamortized Debt Issuance Expense (2.6) (3.6)
Debt Instrument, Unamortized Discount (4.1) (5.5)
Long-term Debt $ 389.5 $ 464.2
Cleveland-Cliffs Inc. [Member] | 7.00% 2027 Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 9.24%  
Long-term Debt, Gross $ 88.0  
Unamortized Debt Issuance Expense (0.3)  
Debt Instrument, Unamortized Discount (9.6)  
Long-term Debt $ 78.1  
Cleveland-Cliffs Inc. [Member] | 5.875% 2027 Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 6.49% 6.49%
Long-term Debt, Gross $ 555.5 $ 750.0
Unamortized Debt Issuance Expense (4.3) (6.3)
Debt Instrument, Unamortized Discount (18.6) (27.3)
Long-term Debt $ 532.6 $ 716.4
Cleveland-Cliffs Inc. [Member] | 6.25% 2040 Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 6.34% 6.34%
Long-term Debt, Gross $ 262.7 $ 298.4
Unamortized Debt Issuance Expense (1.8) (2.2)
Debt Instrument, Unamortized Discount (2.8) (3.3)
Long-term Debt $ 258.1 292.9
Cleveland-Cliffs Inc. [Member] | Credit Facility    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 2.77%  
Long-term Debt, Gross $ 2,000.0 450.0
Long-term Line of Credit $ 400.0 $ 0.0
AK Steel Holding Corporation [Member] | 7.625% 2021 Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 7.33%  
Long-term Debt, Gross $ 33.5  
Unamortized Debt Issuance Expense 0.0  
Debt Instrument, Unamortized Premium 0.1  
Long-term Debt $ 33.6  
AK Steel Holding Corporation [Member] | 7.50% 2023 AK Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 6.17%  
Long-term Debt, Gross $ 12.8  
Unamortized Debt Issuance Expense 0.0  
Debt Instrument, Unamortized Premium 0.5  
Long-term Debt $ 13.3  
AK Steel Holding Corporation [Member] | 6.375% 2025 AK Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 8.11%  
Long-term Debt, Gross $ 38.4  
Unamortized Debt Issuance Expense 0.0  
Debt Instrument, Unamortized Discount (2.7)  
Long-term Debt $ 35.7  
AK Steel Holding Corporation [Member] | 7.00% 2027 AK Senior Notes [Member]    
Debt Instrument [Line Items]    
Debt Instrument, Interest Rate, Effective Percentage 9.24%  
Long-term Debt, Gross $ 56.3  
Unamortized Debt Issuance Expense 0.0  
Debt Instrument, Unamortized Discount (6.0)  
Long-term Debt 50.3  
AK Steel Holding Corporation [Member] | Industrial Revenue Bonds [Member]    
Debt Instrument [Line Items]    
Long-term Debt, Gross 92.0  
Unamortized Debt Issuance Expense 0.0  
Debt Instrument, Unamortized Premium 2.3  
Long-term Debt $ 94.3