ÐÇ¿Õ´«Ã½

Quarterly report pursuant to Section 13 or 15(d)

FAIR VALUE OF FINANCIAL INSTRUMENTS FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value Measurements, Nonrecurring) (Details)

v2.4.0.8
FAIR VALUE OF FINANCIAL INSTRUMENTS FAIR VALUE OF FINANCIAL INSTRUMENTS (Fair Value Measurements, Nonrecurring) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2014
Sep. 30, 2014
Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Impairment Loss Ìý $ 73.5 $ 80.9
Tangible Asset Impairment Charges 7,674.3 7,699.6 Ìý
Assets, Fair Value Disclosure, Nonrecurring 1,457.2 1,457.2 47.9
Impairment of goodwill and other long-lived assets Ìý 7,782.3 318.4
Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring 0 0 0
Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring 0 0 0
Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Assets, Fair Value Disclosure, Nonrecurring 1,457.2 1,457.2 47.9
Amapa [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure Ìý Ìý 0
Equity Method Investment, Other than Temporary Impairment Ìý Ìý 67.6
Amapa [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure Ìý Ìý 0
Amapa [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure Ìý Ìý 0
Amapa [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure Ìý Ìý 0
Global Exploration Investment in Venture [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure 0 0 Ìý
Equity Method Investment, Other than Temporary Impairment Ìý 9.2 Ìý
Global Exploration Investment in Venture [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure 0 0 Ìý
Global Exploration Investment in Venture [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure 0 0 Ìý
Global Exploration Investment in Venture [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Equity Method Investments, Fair Value Disclosure 0 0 Ìý
Asia Pacific Iron Ore [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure 0 0 Ìý
Goodwill, Impairment Loss Ìý 73.5 Ìý
Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure 0 0 Ìý
Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure 0 0 Ìý
Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure 0 0 Ìý
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure Ìý Ìý 0
Goodwill, Impairment Loss Ìý Ìý 80.9
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure Ìý Ìý 0
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure Ìý Ìý 0
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Goodwill, Fair Value Disclosure Ìý Ìý 0
Ferroalloys [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 12.2 12.2 Ìý
Tangible Asset Impairment Charges Ìý 259.5 Ìý
Ferroalloys [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Ferroalloys [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Ferroalloys [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 12.2 12.2 Ìý
Other Reporting Units [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Tangible Asset Impairment Charges Ìý 3.1 Ìý
Other Reporting Units [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Other Reporting Units [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Other Reporting Units [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure Ìý Ìý 46.3
Tangible Asset Impairment Charges Ìý Ìý 155.4
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure Ìý Ìý 0
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure Ìý Ìý 0
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure Ìý Ìý 46.3
Wabush [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Other Asset Impairment Charges Ìý Ìý 14.5
Finite-lived Intangible Assets, Fair Value Disclosure Ìý Ìý 1.6
Wabush [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Finite-lived Intangible Assets, Fair Value Disclosure Ìý Ìý 0
Wabush [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Finite-lived Intangible Assets, Fair Value Disclosure Ìý Ìý 0
Wabush [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Finite-lived Intangible Assets, Fair Value Disclosure Ìý Ìý 1.6
Oak Grove [Member] | North American Coal [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 58.2 58.2 Ìý
Tangible Asset Impairment Charges Ìý 237.8 Ìý
Oak Grove [Member] | North American Coal [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Oak Grove [Member] | North American Coal [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Oak Grove [Member] | North American Coal [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 58.2 58.2 Ìý
CLCC [Member] | North American Coal [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 62.6 62.6 Ìý
Tangible Asset Impairment Charges Ìý 195.5 Ìý
CLCC [Member] | North American Coal [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
CLCC [Member] | North American Coal [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
CLCC [Member] | North American Coal [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 62.6 62.6 Ìý
Bloom Lake [Member] | Eastern Canadian Iron Ore [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 937.2 937.2 Ìý
Tangible Asset Impairment Charges Ìý 6,279.2 Ìý
Bloom Lake [Member] | Eastern Canadian Iron Ore [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Bloom Lake [Member] | Eastern Canadian Iron Ore [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Bloom Lake [Member] | Eastern Canadian Iron Ore [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 937.2 937.2 Ìý
Asia Pacific [Member] | Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 0 0 Ìý
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 343.4 343.4 Ìý
Tangible Asset Impairment Charges Ìý 291.9 Ìý
Other Asset Impairment Charges Ìý 10.1 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 11.9 11.9 Ìý
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 0 0 Ìý
Asia Pacific Iron Ore [Member] | Asia Pacific Iron Ore [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 343.4 343.4 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 11.9 11.9 Ìý
Wabush [Member] | Eastern Canadian Iron Ore [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 1.0 1.0 Ìý
Tangible Asset Impairment Charges Ìý 12.8 Ìý
Other Asset Impairment Charges Ìý 15.2 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 0 0 Ìý
Wabush [Member] | Eastern Canadian Iron Ore [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 0 0 Ìý
Wabush [Member] | Eastern Canadian Iron Ore [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 0 0 Ìý
Wabush [Member] | Eastern Canadian Iron Ore [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 1.0 1.0 Ìý
Finite-lived Intangible Assets, Fair Value Disclosure 0 0 Ìý
Pinnacle [Member] | North American Coal [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 30.7 30.7 Ìý
Tangible Asset Impairment Charges Ìý 394.5 Ìý
Pinnacle [Member] | North American Coal [Member] | Fair Value, Inputs, Level 1 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Pinnacle [Member] | North American Coal [Member] | Fair Value, Inputs, Level 2 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure 0 0 Ìý
Pinnacle [Member] | North American Coal [Member] | Fair Value, Inputs, Level 3 [Member]
 Ìý Ìý Ìý
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Ìý Ìý Ìý
Property, Plant, and Equipment, Fair Value Disclosure $ 30.7 $ 30.7 Ìý