BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Schedule Of Subsidiaries) (Details) |
12 Months Ended | |
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Dec. 31, 2018 |
Dec. 31, 2017 |
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| Related Party Transaction [Line Items] | Ìý | Ìý |
| Noncontrolling Interest, Ownership Percentage by Parent | 100.00% | Ìý |
| Northshore [Member] | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Entity Address, State or Province | Minnesota | Ìý |
| United Taconite [Member] | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Entity Address, State or Province | Minnesota | Ìý |
| Tilden [Member] | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Entity Address, State or Province | Michigan | Ìý |
| Noncontrolling Interest, Ownership Percentage by Parent | Ìý | 100.00% |
| Empire [Member] | Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Entity Address, State or Province | Michigan | Ìý |
| Noncontrolling Interest, Ownership Percentage by Parent | Ìý | 100.00% |
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- Definition Name of the state or province. No definition available.
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- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. No definition available.
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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. No definition available.
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