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Fair Value Of Financial Instruments (Schedule Of Quantitative Inputs And Assumptions For Level 3 Assets And Liabilities) (Detail) (USD $)
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6 Months Ended | |||||||||||||||||
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Jun. 30, 2012
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Mar. 31, 2012
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Dec. 31, 2011
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Jun. 30, 2011
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Mar. 31, 2011
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Dec. 31, 2010
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Jun. 30, 2012
Customer Supply Agreement [Member]
Derivative Asset [Member]
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Jun. 30, 2012
Provisional Pricing Arrangement [Member]
Derivative Asset [Member]
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Jun. 30, 2012
Provisional Pricing Arrangement [Member]
Accounts Receivable [Member]
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Jun. 30, 2012
Provisional Pricing Arrangement [Member]
Other Current Liabilities [Member]
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Jun. 30, 2012
Hot-Rolled Steel Estimate [Member]
Market Approach [Member]
Customer Supply Agreement [Member]
Derivative Asset [Member]
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Jun. 30, 2012
Hot-Rolled Steel Estimate [Member]
Market Approach [Member]
Customer Supply Agreement [Member]
Derivative Asset [Member]
Minimum [Member]
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Jun. 30, 2012
Hot-Rolled Steel Estimate [Member]
Market Approach [Member]
Customer Supply Agreement [Member]
Derivative Asset [Member]
Maximum [Member]
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Jun. 30, 2012
Managements Estimate Of 62% Fe [Member]
Market Approach [Member]
Provisional Pricing Arrangement [Member]
Derivative Asset [Member]
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Jun. 30, 2012
Managements Estimate Of 62% Fe [Member]
Market Approach [Member]
Provisional Pricing Arrangement [Member]
Derivative Asset [Member]
Minimum [Member]
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Jun. 30, 2012
Managements Estimate Of 62% Fe [Member]
Market Approach [Member]
Provisional Pricing Arrangement [Member]
Derivative Asset [Member]
Maximum [Member]
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Jun. 30, 2012
Managements Estimate Of 62% Fe [Member]
Market Approach [Member]
Provisional Pricing Arrangement [Member]
Accounts Receivable [Member]
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Jun. 30, 2012
Managements Estimate Of 62% Fe [Member]
Market Approach [Member]
Provisional Pricing Arrangement [Member]
Other Current Liabilities [Member]
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| Fair Value, Assets And Liabilities Measured On Unobservable Inputs [Line Items] | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Fair value measurement with unobservable inputs derivative asset range | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ (675,000,000) | $ 650,000,000 | $ 775,000,000 | $ (148,000,000) | $ 140,000,000 | $ 160,000,000 | Ìý | Ìý |
| Fair Value of derivative assets | 83,900,000 | 69,200,000 | 157,900,000 | 64,000,000 | 68,100,000 | 45,600,000 | Ìý | Ìý | Ìý | Ìý | 61,400,000 | Ìý | Ìý | 3,300,000 | Ìý | Ìý | 19,200,000 | Ìý |
| Fair Value of derivative liabilities | $ (15.8) | $ (1.1) | $ (19.5) | ÌýÌý | ÌýÌý | ÌýÌý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | $ 15,800,000 |
| Description of Location of Price Risk Derivatives on Balance Sheet | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Derivative Assets | Derivative Assets | Accounts receivable | Other current liabilities | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |