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Basis Of Presentation And Significant Accounting Policies (Schedule Of Subsidiaries) (Detail)
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9 Months Ended | |
|---|---|---|
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Sep. 30, 2012
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Sep. 30, 2011
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Northshore [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Minnesota | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Iron Ore | Ìý |
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United Taconite [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Minnesota | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Iron Ore | Ìý |
|
Wabush [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Labrador/Quebec, Canada | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Iron Ore | Ìý |
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Bloom Lake [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Quebec, Canada | Ìý |
| Ownership interest, percent | 75.00% | 75.00% |
| Operation | Iron Ore | Ìý |
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Tilden [Member]
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Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Michigan | Ìý |
| Ownership interest, percent | 85.00% | 85.00% |
| Operation | Iron Ore | Ìý |
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Empire [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Michigan | Ìý |
| Ownership interest, percent | 79.00% | 79.00% |
| Operation | Iron Ore | Ìý |
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Koolyanobbing [Member]
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Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Western Australia | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Iron Ore | Ìý |
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Pinnacle [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | West Virginia | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Coal | Ìý |
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Oak Grove [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | Alabama | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Coal | Ìý |
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CLCC [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Location | West Virginia | Ìý |
| Ownership interest, percent | 100.00% | Ìý |
| Operation | Coal | Ìý |