|
Related Parties (Summary Of Other Ownership Interests) (Details)
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Mar. 31, 2012
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Mar. 31, 2011
|
|---|---|---|
|
Empire [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 79.00% | 79.00% |
|
Tilden [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 85.00% | 85.00% |
|
Bloom Lake [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 75.00% | 75.00% |
|
Cliffs Natural Resources [Member] | Empire [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 79.00% | Ìý |
|
Cliffs Natural Resources [Member] | Tilden [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 85.00% | Ìý |
|
Cliffs Natural Resources [Member] | Hibbing [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 23.00% | Ìý |
|
Cliffs Natural Resources [Member] | Bloom Lake [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 75.00% | Ìý |
|
Arcelor Mittal [Member] | Empire [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 21.00% | Ìý |
|
Arcelor Mittal [Member] | Hibbing [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 62.30% | Ìý |
|
U. S. Steel Canada | Tilden [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 15.00% | Ìý |
|
U. S. Steel Canada | Hibbing [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 14.70% | Ìý |
|
WISCO [Member] | Bloom Lake [Member]
|
Ìý | Ìý |
| Related Party Transaction [Line Items] | Ìý | Ìý |
| Ownership Interest | 25.00% | Ìý |