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DERIVATIVE INSTRUMENTS AND HEDGING ACTIVITIES (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | |||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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Jun. 30, 2014
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Jun. 30, 2013
|
Jun. 30, 2014
|
Jun. 30, 2013
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
|
Jun. 30, 2013
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
|
Jun. 30, 2013
Canadian Dollar Foreign Exchange Contracts Hedge Prior to De Designation [Member]
|
Jun. 30, 2014
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Designated as Hedging Instrument [Member]
|
Dec. 31, 2013
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Designated as Hedging Instrument [Member]
|
Jun. 30, 2014
Australian Dollar Foreign Exchange Contract Hedge Designation [Member]
Designated as Hedging Instrument [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Cost of Sales [Member]
|
Jun. 30, 2013
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Cost of Sales [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Cost of Sales [Member]
|
Jun. 30, 2013
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Cost of Sales [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Designated as Hedging Instrument [Member]
|
Dec. 31, 2013
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Designated as Hedging Instrument [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge Designation [Member]
Designated as Hedging Instrument [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
|
Jun. 30, 2014
Interest Rate Swap [Member]
Other Nonoperating Income Expense [Member]
|
Jun. 30, 2014
Interest Rate Swap [Member]
Other Nonoperating Income Expense [Member]
|
Jun. 30, 2014
Interest Rate Swap [Member]
Designated as Hedging Instrument [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member]
Not Designated as Hedging Instrument [Member]
|
Dec. 31, 2013
Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member]
Not Designated as Hedging Instrument [Member]
|
Jun. 30, 2014
Canadian Dollar Foreign Exchange Contracts Hedge De Designated [Member] [Member]
Not Designated as Hedging Instrument [Member]
Accumulated Other Comprehensive Income (Loss) [Member]
|
Jun. 30, 2014
Foreign Exchange Contract [Member]
Cost of Sales [Member]
|
Jun. 30, 2014
Foreign Exchange Contract [Member]
Cost of Sales [Member]
|
Jun. 30, 2013
Foreign Exchange Contract [Member]
Cost of Sales [Member]
|
Jun. 30, 2014
Customer Supply Agreement [Member]
Not Designated as Hedging Instrument [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Customer Supply Agreement [Member]
Not Designated as Hedging Instrument [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Customer Supply Agreement [Member]
Not Designated as Hedging Instrument [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Customer Supply Agreement [Member]
Not Designated as Hedging Instrument [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Customer Supply Agreement [Member]
Not Designated as Hedging Instrument [Member]
Derivative Financial Instruments, Assets [Member]
|
Dec. 31, 2013
Customer Supply Agreement [Member]
Not Designated as Hedging Instrument [Member]
Derivative Financial Instruments, Assets [Member]
|
Jun. 30, 2014
Provisional Pricing Arrangements [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Provisional Pricing Arrangements [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Provisional Pricing Arrangements [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Provisional Pricing Arrangements [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member]
Product Revenues [Member]
|
Jun. 30, 2013
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member]
Derivative Financial Instruments, Assets [Member]
|
Dec. 31, 2013
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member]
Derivative Financial Instruments, Assets [Member]
|
Dec. 31, 2013
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U.S. Iron Ore, Eastern Canadian Iron Ore And Asia Pacific Iron Ore [Member]
Derivative Financial Instruments, Liabilities [Member]
|
Jun. 30, 2014
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U S Iron Ore And Asia Pacific Iron Ore [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U S Iron Ore And Asia Pacific Iron Ore [Member]
Product Revenues [Member]
|
Jun. 30, 2014
Provisional Pricing Arrangements [Member]
Not Designated as Hedging Instrument [Member]
U S Iron Ore And Asia Pacific Iron Ore [Member]
Derivative Financial Instruments, Liabilities [Member]
|
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| Derivative [Line Items] | |||||||||||||||||||||||||||||||||||||||||||||||||
| Derivative, Notional Amount | $ 300.0 | $ 323.0 | $ 259.1 | $ 285.9 | $ 250.0 | $ 0 | $ 74.8 | ||||||||||||||||||||||||||||||||||||||||||
| Gain (Loss) on Fair Value Hedge Ineffectiveness, Net | 0.1 | 0.3 | |||||||||||||||||||||||||||||||||||||||||||||||
| Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net | 17.8 | 7.2 | 38.5 | 28.4 | (2.4) | (3.3) | 0 | (14.1) | (28.2) | (20.2) | (31.1) | ||||||||||||||||||||||||||||||||||||||
| Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion, Net | (6.6) | 2.2 | (19.4) | 4.2 | (0.2) | 0 | (0.5) | 0 | (3.7) | 2.6 | (12.8) | 4.4 | (2.7) | (0.4) | (6.1) | (0.2) | |||||||||||||||||||||||||||||||||
| Amount that will be reclassified to product revenues in the next 12 months upon settlement of the related contracts | 6.8 | 1.4 | 0 | ||||||||||||||||||||||||||||||||||||||||||||||
| Amount of gain/(loss) recognized in income on derivative | 34.3 | 35.4 | 62.0 | 59.5 | (28.2) | (31.1) | (14.1) | (20.2) | |||||||||||||||||||||||||||||||||||||||||
| Derivative assets | 33.0 | 55.8 | 0 | 3.1 | |||||||||||||||||||||||||||||||||||||||||||||
| Derivative liabilities | $ 10.3 | $ 20.2 | |||||||||||||||||||||||||||||||||||||||||||||||