Annual report pursuant to Section 13 and 15(d)

FAIR VALUE OF FINANCIAL INSTRUMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details)

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FAIR VALUE OF FINANCIAL INSTRUMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) (USD $)
Dec. 31, 2012
Dec. 31, 2011
Long-term debt:    
Long-term debt, face amount $ 5,497,100,000 $ 5,447,000,000
Total long-term debt, carrying value 3,960,700,000 3,608,700,000
Term Loan - $1.25 Billion [Member]
    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Term Loan Original Amount 1,250,000,000 1,250,000,000
Long-term debt:    
Long-term debt, face amount 847,100,000 [1] 972,000,000
Senior Notes - $700 Million [Member]
    
Long-term debt:    
Long-term debt, face amount 700,000,000 700,000,000
Senior Notes - $1.3 Billion [Member]
    
Long-term debt:    
Long-term debt, face amount 1,300,000,000 1,300,000,000
Senior Notes - $400 Million [Member]
    
Long-term debt:    
Long-term debt, face amount 400,000,000 400,000,000
Senior Notes - $325 Million [Member]
    
Long-term debt:    
Long-term debt, face amount 325,000,000 325,000,000
Senior Notes - $500 Million [Member]
    
Long-term debt:    
Long-term debt, face amount 500,000,000 500,000,000
Revolving Loan [Member]
    
Long-term debt:    
Long-term debt, face amount 1,750,000,000 1,750,000,000
Revolving loan, carrying value 325,000,000 [2] 0 [2]
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member]
    
Receivables:    
Receivables, carrying value 52,500,000 58,800,000
Long-term debt:    
Total long-term debt, carrying value 3,960,700,000 3,608,700,000
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member] | Customer Supplemental Payments [Member]
    
Receivables:    
Receivables, carrying value 22,300,000 22,300,000
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member] | ArcelorMittal USA - Receivable [Member]
    
Receivables:    
Receivables, carrying value 19,300,000 26,500,000
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member] | Other Credit Receivable [Member]
    
Receivables:    
Receivables, carrying value 10,900,000 10,000,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member]
    
Receivables:    
Receivables, fair value 53,500,000 61,500,000
Long-term debt:    
Total long-term debt, fair value 4,354,800,000 3,820,500,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] | Customer Supplemental Payments [Member]
    
Receivables:    
Receivables, fair value 21,300,000 20,800,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] | ArcelorMittal USA - Receivable [Member]
    
Receivables:    
Receivables, fair value 21,300,000 30,700,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] | Other Credit Receivable [Member]
    
Receivables:    
Receivables, fair value 10,900,000 10,000,000
Significant Other Observable Inputs (Level 2) [Member] | Term Loan - $1.25 Billion [Member] | Carrying Value [Member]
    
Long-term debt:    
Term loan, carrying value 753,000,000 897,200,000
Significant Other Observable Inputs (Level 2) [Member] | Term Loan - $1.25 Billion [Member] | Fair Value [Member]
    
Long-term debt:    
Term loan, fair value 753,000,000 897,200,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $700 Million [Member] | Carrying Value [Member]
    
Long-term debt:    
Senior notes, carrying value 699,400,000 699,300,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $700 Million [Member] | Fair Value [Member]
    
Long-term debt:    
Senior notes, fair value 759,400,000 726,400,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $1.3 Billion [Member] | Carrying Value [Member]
    
Long-term debt:    
Senior notes, carrying value 1,289,400,000 1,289,200,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $1.3 Billion [Member] | Fair Value [Member]
    
Long-term debt:    
Senior notes, fair value 1,524,700,000 1,399,400,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $400 Million [Member] | Carrying Value [Member]
    
Long-term debt:    
Senior notes, carrying value 398,200,000 398,000,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $400 Million [Member] | Fair Value [Member]
    
Long-term debt:    
Senior notes, fair value 464,300,000 448,800,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $325 Million [Member] | Carrying Value [Member]
    
Long-term debt:    
Senior notes, carrying value 0 325,000,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $325 Million [Member] | Fair Value [Member]
    
Long-term debt:    
Senior notes, fair value 0 348,700,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $500 Million [Member] | Carrying Value [Member]
    
Long-term debt:    
Senior notes, carrying value 495,700,000 0
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $500 Million [Member] | Fair Value [Member]
    
Long-term debt:    
Senior notes, fair value 528,400,000 0
Significant Other Observable Inputs (Level 2) [Member] | Revolving Loan [Member] | Carrying Value [Member]
    
Long-term debt:    
Revolving loan, carrying value 325,000,000 0
Significant Other Observable Inputs (Level 2) [Member] | Revolving Loan [Member] | Fair Value [Member]
    
Long-term debt:    
Revolving loan, fair value $ 325,000,000 $ 0
[1] As of December 31, 2012 and December 31, 2011, $402.8 million and $278.0 million, respectively, had been paid down on the original $1.25 billion term loan and, of the remaining term loan, $94.1 million and $74.8 million, respectively, was classified as Current portion of debt. The current classification is based upon the principal payment terms of the arrangement requiring principal payments on each three-month anniversary following the funding of the term loan.
[2] As of December 31, 2012 and December 31, 2011, $325.0 million and no revolving loans were drawn under the credit facility, respectively, and the principal amount of letter of credit obligations totaled $27.7 million and $23.5 million for each period, respectively, thereby reducing available borrowing capacity to $1.4 billion and $1.7 billion for each period, respectively.