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FAIR VALUE OF FINANCIAL INSTRUMENTS (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 3 Months Ended | 12 Months Ended | 3 Months Ended | 12 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Mar. 31, 2013
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Mar. 31, 2012
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Dec. 31, 2012
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Mar. 31, 2013
Empire [Member]
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Dec. 31, 2012
Empire [Member]
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Dec. 31, 2002
Empire [Member]
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Dec. 31, 2002
Prior [Member]
Empire [Member]
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Dec. 31, 2002
Current [Member]
Empire [Member]
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Mar. 31, 2013
Other Current Assets [Member]
Empire [Member]
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Dec. 31, 2012
Other Current Assets [Member]
Empire [Member]
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Mar. 31, 2013
U.S. Iron Ore [Member]
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Dec. 31, 2012
U.S. Iron Ore [Member]
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Dec. 31, 2012
Amapa [Member]
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Dec. 31, 2012
Equity Method Investments [Member]
Amapa [Member]
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Mar. 31, 2013
Equity Method Investments [Member]
Amapa [Member]
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| Fair Value, Assets And Liabilities Components [Line Items] | |||||||||||||||
| Transfer of derivative assets from level 3 to level 2 | $ 0 | $ 0 | |||||||||||||
| Transfer of derivative assets from level 2 to level 3 | 0 | 0 | |||||||||||||
| Management Estimate of 62% Fe | 62.00% | ||||||||||||||
| Maximum deferred portion of supplemental payments | 22.3 | ||||||||||||||
| Supply agreement, customer receivable, stated interest rate | 9.00% | ||||||||||||||
| Supply agreement, customer receivable, description of variable rate basis | prime rate | ||||||||||||||
| Other current assets | 297.9 | 321.6 | 16.7 | 22.3 | |||||||||||
| Supply agreement, customer receivable, basis spread on variable rate | 3.50% | ||||||||||||||
| Fair value of the receivable | 19.1 | 21.3 | 16.1 | 21.3 | |||||||||||
| Estimated credit-adjusted risk-free interest rate | 2.24% | 2.85% | 2.14% | 2.81% | |||||||||||
| Interest Percentage | 46.70% | 30.00% | |||||||||||||
| Equity Method Investments, Fair Value Disclosure | 72.5 | ||||||||||||||
| Percent ownership interest after transaction | 79.00% | ||||||||||||||
| Long term accounts notes and loans receivable net noncurrent | 17.4 | 19.3 | 120.0 | 10.0 | 10.0 | ||||||||||
| Impairment of equity method investment | $ 365.4 | ||||||||||||||
| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
Loans Receivable, Interest Rate, Stated Percentage No definition available.
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| X | ||||||||||
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- Definition
Management Estimate of 62% Fe No definition available.
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| X | ||||||||||
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- Definition
Maximum deferred portion of supplemental payments No definition available.
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| X | ||||||||||
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- Definition
This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. Amounts due from customers or clients for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, as well as any other amounts due from others, including related parties, which may be included in accounts receivable as categorized on the statement of financial position. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents investments accounted for under the equity method of accounting as of the balance sheet date. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Risk-free interest rate assumption used in valuing an instrument. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Transfers into assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Transfers out of assets measured at fair value and categorized within Level 3 of the fair value hierarchy that have taken place during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The percentage points (also referred to as 'margin') added to the reference rate as stated in the loan agreement and used to compute the variable rate on the loans receivable. For instance, the loan agreement might state that the interest rate the borrower is obligated to pay is the London Interbank Offered Rate (LIBOR) plus three quarters (3/4) of a percentage point adjusted quarterly (each three months). LIBOR in this example is the index or reference rate, 3/4 percentage point is the margin, the reference rate plus the margin is the fully indexed rate. This element would be used to report separately the margin. No definition available.
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| X | ||||||||||
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- Definition
The reference rate for the variable rate of the loans receivable, such as LIBOR or the US Treasury rate and the maturity of the reference rate used, such as three months or six months LIBOR. No definition available.
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| X | ||||||||||
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- Definition
The aggregate of amounts due from customers or clients more than one year from the balance sheet date, for goods or services that have been delivered or sold in the normal course of business and an amount representing an agreement for an unconditional promise by the maker to pay the Company (holder) a definite sum of money at a future date more than one year from the balance sheet date, reduced to their estimated net realizable fair value by an allowance established by the Company of the amount it deems uncertain of collection and net of any write-downs taken for collection uncertainty on the part of the holder, respectively. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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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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| X | ||||||||||
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- Definition
Aggregate carrying amount, as of the balance sheet date, of current assets not separately disclosed in the balance sheet. Current assets are expected to be realized or consumed within one year (or the normal operating cycle, if longer). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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