FAIR VALUE OF FINANCIAL INSTRUMENTS FAIR VALUE OF FINANCIAL INSTRUMENTS (Impairment Charges on Financial and Nonfinancial Assets) (Details) (USD $) In Millions, unless otherwise specified
|
12 Months Ended |
Dec. 31, 2013
|
Dec. 31, 2012
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Impairment Loss |
$ 80.9
|
$ 1,000.0
|
Assets, Fair Value Disclosure, Nonrecurring |
47.9
|
72.5
|
Impairment Charges |
318.4
|
1,415.3
|
Fair Value, Inputs, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Assets, Fair Value Disclosure, Nonrecurring |
0
|
0
|
Fair Value, Inputs, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Assets, Fair Value Disclosure, Nonrecurring |
0
|
0
|
Fair Value, Inputs, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Assets, Fair Value Disclosure, Nonrecurring |
47.9
|
72.5
|
Amapa [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Equity Method Investments, Fair Value Disclosure |
0
|
72.5
|
Equity Method Investment, Other than Temporary Impairment |
67.6
|
365.4
|
Amapa [Member] | Fair Value, Inputs, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Equity Method Investments, Fair Value Disclosure |
0
|
0
|
Amapa [Member] | Fair Value, Inputs, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Equity Method Investments, Fair Value Disclosure |
0
|
0
|
Amapa [Member] | Fair Value, Inputs, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Equity Method Investments, Fair Value Disclosure |
0
|
72.5
|
Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Impairment Loss |
80.9
|
|
Wabush [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
|
0
|
Goodwill, Impairment Loss |
|
2.7
|
Property, Plant, and Equipment, Fair Value Disclosure |
|
0
|
Impairment of Long-Lived Assets Held-for-use |
140.1
|
49.9
|
Finite-lived Intangible Assets, Fair Value Disclosure |
1.6
|
|
Other Asset Impairment Charges |
14.5
|
|
Wabush [Member] | Fair Value, Inputs, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
|
0
|
Property, Plant, and Equipment, Fair Value Disclosure |
|
0
|
Finite-lived Intangible Assets, Fair Value Disclosure |
0
|
|
Wabush [Member] | Fair Value, Inputs, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
|
0
|
Property, Plant, and Equipment, Fair Value Disclosure |
|
0
|
Finite-lived Intangible Assets, Fair Value Disclosure |
0
|
|
Wabush [Member] | Fair Value, Inputs, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
|
0
|
Property, Plant, and Equipment, Fair Value Disclosure |
|
0
|
Finite-lived Intangible Assets, Fair Value Disclosure |
1.6
|
|
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Property, Plant, and Equipment, Fair Value Disclosure |
46.3
|
|
Impairment of Long-Lived Assets Held-for-use |
155.4
|
|
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Property, Plant, and Equipment, Fair Value Disclosure |
0
|
|
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Property, Plant, and Equipment, Fair Value Disclosure |
0
|
|
Wabush and Cliffs Chromite Ontario and Cliffs Chromite Far North [Member] | Fair Value, Inputs, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Property, Plant, and Equipment, Fair Value Disclosure |
46.3
|
|
CQIM Reporting Unit [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
0
|
0
|
Goodwill, Impairment Loss |
|
997.3
|
CQIM Reporting Unit [Member] | Fair Value, Inputs, Level 1 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
0
|
0
|
CQIM Reporting Unit [Member] | Fair Value, Inputs, Level 2 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
0
|
0
|
CQIM Reporting Unit [Member] | Fair Value, Inputs, Level 3 [Member]
|
|
|
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |
|
|
Goodwill, Fair Value Disclosure |
$ 0
|
$ 0
|