FAIR VALUE OF FINANCIAL INSTRUMENTS (Carrying Value And Fair Value Of Financial Instruments Disclosure) (Details) (USD $)	Sep. 30, 2013		Dec. 31, 2012
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	$ 4,712,100,000		$ 5,497,100,000
Long-term debt:
Term loan, carrying value	3,327,500,000		4,054,800,000
Total long-term debt, carrying value	3,319,600,000		3,960,700,000
Term Loan - $1.25 Billion [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount			847,100,000
Term Loan Original Amount	0		1,250,000,000
Long-term debt:
Term loan, carrying value			847,100,000	[1]
Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	700,000,000		700,000,000
Long-term debt:
Term loan, carrying value	699,400,000	[2]	699,400,000	[2]
Senior Notes - $1.3 Billion [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	1,300,000,000.0		1,300,000,000.0
Senior Notes - $400 Million [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	400,000,000		400,000,000
Long-term debt:
Term loan, carrying value	398,400,000	[3]	398,200,000	[3]
Senior Notes - $500 Million [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	500,000,000.0		500,000,000.0
Long-term debt:
Term loan, carrying value	496,300,000	[4]	495,700,000	[4]
Revolving Credit Facility [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	1,750,000,000.00		1,750,000,000.00
Long-term debt:
Revolving loan, carrying value	380,000,000	[5]	325,000,000	[5]
Equipment Loans [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Debt Instrument, Face Amount	62,100,000
Long-term debt:
Term loan, carrying value	62,100,000
Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	1,700,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts Receivable, Fair Value Disclosure	24,400,000		53,500,000
Long-term debt:
Total long-term debt, fair value	3,565,400,000		4,354,800,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Customer Supplemental Payments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts Receivable, Fair Value Disclosure	0		21,300,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | ArcelorMittal USA - Receivable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts Receivable, Fair Value Disclosure	14,300,000		21,300,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Other Credit Receivable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts Receivable, Fair Value Disclosure	10,100,000		10,900,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Term Loan - $1.25 Billion [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	0		753,000,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	719,200,000		759,400,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $1.3 Billion [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	1,442,200,000		1,524,700,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $400 Million [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	439,700,000		464,300,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $500 Million [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	528,400,000		528,400,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, fair value	380,000,000		325,000,000
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Equipment Loans [Member]
Long-term debt:
Debt Instrument, Fair Value Disclosure	54,200,000		0
Portion at Fair Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	1,700,000		0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts, Notes, Loans and Financing Receivable, Net, Noncurrent	23,500,000		52,500,000
Long-term debt:
Total long-term debt, carrying value	3,319,600,000		3,960,700,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Customer Supplemental Payments [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts, Notes, Loans and Financing Receivable, Net, Noncurrent	0		22,300,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | ArcelorMittal USA - Receivable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts, Notes, Loans and Financing Receivable, Net, Noncurrent	13,400,000		19,300,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Other Credit Receivable [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Accounts, Notes, Loans and Financing Receivable, Net, Noncurrent	10,100,000		10,900,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Term Loan - $1.25 Billion [Member]
Long-term debt:
Term loan, carrying value	0		753,000,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Seven Hundred Million Four Point Eight Seven Five Two Thousand Twenty-one Senior Note [Member]
Long-term debt:
Senior notes, carrying value	699,400,000		699,400,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $1.3 Billion [Member]
Long-term debt:
Senior notes, carrying value	1,289,600,000		1,289,400,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $400 Million [Member]
Long-term debt:
Senior notes, carrying value	398,400,000		398,200,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Senior Notes - $500 Million [Member]
Long-term debt:
Senior notes, carrying value	496,300,000		495,700,000.0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Revolving Credit Facility [Member]
Long-term debt:
Revolving loan, carrying value	380,000,000		325,000,000
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Equipment Loans [Member]
Long-term debt:
Term loan, carrying value	54,200,000		0
Reported Value Measurement [Member] | Fair Value, Inputs, Level 2 [Member] | Interest Rate Swap [Member]
Long-term debt:
Fair Value Adjustment to Interest Rate Hedge	$ 1,700,000		$ 0

[1] During the first quarter of 2013, the term loan was repaid in full through repayments totaling $847.1 million. As of December 31, 2012, $402.8 million had been paid on the original $1.25 billion term loan and, of the remaining term loan, $94.1 million was classified as Current portion of debt. The current classification was 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 September 30, 2013 and December 31, 2012, the $700 million 4.875 percent senior notes were recorded at a par value of $700 million less unamortized discounts of $0.6 million for each period, based on an imputed interest rate of 4.89 percent.

[3] As of September 30, 2013 and December 31, 2012, the $400 million 5.90 percent senior notes were recorded at a par value of $400 million less unamortized discounts of $1.6 million and $1.8 million, respectively, based on an imputed interest rate of 5.98 percent.

[4] As of September 30, 2013 and December 31, 2012, the $500 million 3.95 percent senior notes were recorded at a par value of $500 million less unamortized discounts of $3.7 million and $4.3 million, respectively, based on an imputed interest rate of 4.14 percent.

[5] As of September 30, 2013 and December 31, 2012, $380.0 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.