Annual report pursuant to Section 13 and 15(d)

DEBT AND CREDIT FACILITIES - Debt Redemption (Details)

v3.20.4
DEBT AND CREDIT FACILITIES - Debt Redemption (Details)
 12 Months Ended
Dec. 31, 2020
9.875% 2025 Senior Secured Notes | Debt Instrument, Redemption, Period One, Upon Equity Issuance | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 109.875%
9.875% 2025 Senior Secured Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
9.875% 2025 Senior Secured Notes | Debt Instrument, Redemption, Period Two | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 107.406%
9.875% 2025 Senior Secured Notes | Debt Instrument, Redemption, Period Three | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 104.938%
9.875% 2025 Senior Secured Notes | Debt Instrument, Redemption, Period Four | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 102.469%
9.875% 2025 Senior Secured Notes | Debt Instrument, Redemption, Period Five [Member] | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
6.75% 2026 Senior Secured Notes | Debt Instrument, Redemption, Period One, Upon Equity Issuance | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 106.75%
6.75% 2026 Senior Secured Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
6.75% 2026 Senior Secured Notes | Debt Instrument, Redemption, Period Two | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 105.063%
6.75% 2026 Senior Secured Notes | Debt Instrument, Redemption, Period Three | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 103.375%
6.75% 2026 Senior Secured Notes | Debt Instrument, Redemption, Period Four | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.688%
6.75% 2026 Senior Secured Notes | Debt Instrument, Redemption, Period Five [Member] | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
4.875% 2024 Senior Secured Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 102.438%
4.875% 2024 Senior Secured Notes | Debt Instrument, Redemption, Period Two | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.219%
4.875% 2024 Senior Secured Notes | Debt Instrument, Redemption, Period Three | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
6.375% 2025 Senior Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 103.188%
6.375% 2025 Senior Notes | Debt Instrument, Redemption, Period Two | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.594%
6.375% 2025 Senior Notes | Debt Instrument, Redemption, Period Three | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
7.00% 2027 Senior Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
7.00% 2027 Senior Notes | Debt Instrument, Redemption, Period Two | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 103.50%
7.00% 2027 Senior Notes | Debt Instrument, Redemption, Period Three | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 102.333%
7.00% 2027 Senior Notes | Debt Instrument, Redemption, Period Four | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.167%
7.00% 2027 Senior Notes | Debt Instrument, Redemption, Period Five [Member] | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
7.50% 2023 AK Senior Notes [Member] | Debt Instrument, Redemption, Period One | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.875%
7.50% 2023 AK Senior Notes [Member] | Debt Instrument, Redemption, Period Two | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
6.375% 2025 AK Senior Notes | Debt Instrument, Redemption, Period One | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 103.188%
6.375% 2025 AK Senior Notes | Debt Instrument, Redemption, Period Two | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.594%
6.375% 2025 AK Senior Notes | Debt Instrument, Redemption, Period Three | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
7.00% 2027 AK Senior Notes | Debt Instrument, Redemption, Period One | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
7.00% 2027 AK Senior Notes | Debt Instrument, Redemption, Period Two | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 103.50%
7.00% 2027 AK Senior Notes | Debt Instrument, Redemption, Period Three | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 102.333%
7.00% 2027 AK Senior Notes | Debt Instrument, Redemption, Period Four | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 101.167%
7.00% 2027 AK Senior Notes | Debt Instrument, Redemption, Period Five [Member] | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
1.50% 2025 Convertible Senior Notes  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
5.875% 2027 Senior Notes | Debt Instrument, Redemption, Period One, Upon Equity Issuance | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 105.875%
5.875% 2027 Senior Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
6.25% 2040 Senior Notes | Debt Instrument, Redemption, Period One | Cleveland-Cliffs Inc. [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%
7.625% 2021 AK Senior Notes | Debt Instrument, Redemption, Period Two | AK Steel [Member]  
Debt Instrument, Redemption [Line Items]  
Debt Instrument, Redemption Price, Percentage 100.00%