Quarterly report pursuant to Section 13 or 15(d)

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

v2.4.0.8
FAIR VALUE OF FINANCIAL INSTRUMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) (USD $)
Jun. 30, 2013
Dec. 31, 2012
Long-term debt:    
Long-term debt, face amount $ 4,650,000,000 $ 5,497,100,000
Total long-term debt, carrying value 3,323,300,000 3,960,700,000
Term Loan - $1.25 Billion [Member]
   
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Term Loan Original Amount 0 1,250,000,000
Long-term debt:    
Long-term debt, face amount   847,100,000
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 1,300,000,000.0 1,300,000,000.0
Senior Notes - $400 Million [Member]
   
Long-term debt:    
Long-term debt, face amount 400,000,000 400,000,000
Senior Notes - $500 Million [Member]
   
Long-term debt:    
Long-term debt, face amount 500,000,000.0 500,000,000.0
Revolving Loan [Member]
   
Long-term debt:    
Long-term debt, face amount 1,750,000,000.00 1,750,000,000.00
Revolving loan, carrying value 440,000,000 [1] 325,000,000 [1]
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member]
   
Receivables:    
Receivables, carrying value 25,200,000 52,500,000
Long-term debt:    
Total long-term debt, carrying value 3,323,300,000 3,960,700,000
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member] | Customer Supplemental Payments [Member]
   
Receivables:    
Receivables, carrying value 0 22,300,000
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member] | ArcelorMittal USA - Receivable [Member]
   
Receivables:    
Receivables, carrying value 15,400,000 19,300,000
Significant Other Observable Inputs (Level 2) [Member] | Carrying Value [Member] | Other Credit Receivable [Member]
   
Receivables:    
Receivables, carrying value 9,800,000 10,900,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member]
   
Receivables:    
Receivables, fair value 26,500,000 53,500,000
Long-term debt:    
Total long-term debt, fair value 3,564,700,000 4,354,800,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] | Customer Supplemental Payments [Member]
   
Receivables:    
Receivables, fair value 0 21,300,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] | ArcelorMittal USA - Receivable [Member]
   
Receivables:    
Receivables, fair value 16,700,000 21,300,000
Significant Other Observable Inputs (Level 2) [Member] | Fair Value [Member] | Other Credit Receivable [Member]
   
Receivables:    
Receivables, fair value 9,800,000 10,900,000
Significant Other Observable Inputs (Level 2) [Member] | Term Loan - $1.25 Billion [Member] | Carrying Value [Member]
   
Long-term debt:    
Term loan, carrying value 0 753,000,000
Significant Other Observable Inputs (Level 2) [Member] | Term Loan - $1.25 Billion [Member] | Fair Value [Member]
   
Long-term debt:    
Term loan, fair value 0 753,000,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $700 Million [Member] | Carrying Value [Member]
   
Long-term debt:    
Senior notes, carrying value 699,400,000 699,400,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $700 Million [Member] | Fair Value [Member]
   
Long-term debt:    
Senior notes, fair value 718,900,000 759,400,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $1.3 Billion [Member] | Carrying Value [Member]
   
Long-term debt:    
Senior notes, carrying value 1,289,500,000 1,289,400,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $1.3 Billion [Member] | Fair Value [Member]
   
Long-term debt:    
Senior notes, fair value 1,450,600,000 1,524,700,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $400 Million [Member] | Carrying Value [Member]
   
Long-term debt:    
Senior notes, carrying value 398,300,000 398,200,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $400 Million [Member] | Fair Value [Member]
   
Long-term debt:    
Senior notes, fair value 440,500,000 464,300,000
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $500 Million [Member] | Carrying Value [Member]
   
Long-term debt:    
Senior notes, carrying value 496,100,000 495,700,000.0
Significant Other Observable Inputs (Level 2) [Member] | Senior Notes - $500 Million [Member] | Fair Value [Member]
   
Long-term debt:    
Senior notes, fair value 514,700,000 528,400,000.0
Significant Other Observable Inputs (Level 2) [Member] | Revolving Loan [Member] | Carrying Value [Member]
   
Long-term debt:    
Revolving loan, carrying value 440,000,000 325,000,000
Significant Other Observable Inputs (Level 2) [Member] | Revolving Loan [Member] | Fair Value [Member]
   
Long-term debt:    
Revolving loan, fair value $ 440,000,000 $ 325,000,000
[1] As of June 30, 2013 and December 31, 2012, $440.0 million and $325.0 million revolving loans were drawn under the credit facility, respectively, and the principal amount of letter of credit obligations totaled $27.7 million for each period, thereby reducing available borrowing capacity to $1.3 billion and $1.4 billion for each period, respectively.