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.