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DISCONTINUED OPERATIONS Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis - North American Coal (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2015 | Dec. 31, 2014
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Tangible Asset Impairment Charges |  | $ 537.8
Assets, Fair Value Disclosure, Nonrecurring | $ 397.2 | 79.4
Impairment Charges | 269.5 | 644.7
North American Coal [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Property, Plant, and Equipment, Fair Value Disclosure | 20.4 |
Tangible Asset Impairment Charges | 73.4 |
Assets, Fair Value Disclosure, Nonrecurring | 20.4 |
Impairment Charges | 73.4 |
Fair Value, Inputs, Level 1 [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Assets, Fair Value Disclosure, Nonrecurring | 0.0 | 0.0
Fair Value, Inputs, Level 1 [Member] | North American Coal [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Property, Plant, and Equipment, Fair Value Disclosure | 0.0 |
Assets, Fair Value Disclosure, Nonrecurring | 0.0 |
Fair Value, Inputs, Level 2 [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Assets, Fair Value Disclosure, Nonrecurring | 397.2 | 0.0
Fair Value, Inputs, Level 2 [Member] | North American Coal [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Property, Plant, and Equipment, Fair Value Disclosure | 0.0 |
Assets, Fair Value Disclosure, Nonrecurring | 0.0 |
Fair Value, Inputs, Level 3 [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Assets, Fair Value Disclosure, Nonrecurring | 0.0 | $ 79.4
Fair Value, Inputs, Level 3 [Member] | North American Coal [Member] |  |
Discontinued Operations, Items Measured at Fair Value on a Non-Recurring Basis [Line Items] |  |
Property, Plant, and Equipment, Fair Value Disclosure | 20.4 |
Assets, Fair Value Disclosure, Nonrecurring | $ 20.4 |

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