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Quarterly report pursuant to Section 13 or 15(d)

Fair Value Of Financial Instruments (Narrative) (Details)

v2.4.0.6
Fair Value Of Financial Instruments (Narrative) (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended
Mar. 31, 2012
Dec. 31, 2011
Dec. 31, 2002
Fair Value, Assets And Liabilities Components [Line Items] Ìý Ìý Ìý
Interest rate on long term receivable the higher of 9 percent or the prime rate plus 350 basis points Ìý Ìý
Other non-current assets $ 186.8 $ 191.2 Ìý
U.S. Iron Ore [Member]
Ìý Ìý Ìý
Fair Value, Assets And Liabilities Components [Line Items] Ìý Ìý Ìý
Maximum deferred portion of supplemental payments 22.3 Ìý Ìý
Other non-current assets 22.3 Ìý Ìý
Fair value of the receivable 21.2 20.8 Ìý
Estimated credit-adjusted risk-free interest rate 3.30% Ìý Ìý
Empire [Member]
Ìý Ìý Ìý
Fair Value, Assets And Liabilities Components [Line Items] Ìý Ìý Ìý
Long term accounts notes and loans receivable net noncurrent 24.8 26.5 120.0
Fair value of the receivable $ 28.6 $ 30.7 Ìý
Estimated credit-adjusted risk-free interest rate 2.02% Ìý Ìý
Current [Member] | Empire [Member]
Ìý Ìý Ìý
Fair Value, Assets And Liabilities Components [Line Items] Ìý Ìý Ìý
Percent ownership interest Ìý Ìý 79.00%
Prior [Member] | Empire [Member]
Ìý Ìý Ìý
Fair Value, Assets And Liabilities Components [Line Items] Ìý Ìý Ìý
Percent ownership interest Ìý Ìý 46.70%