REVENUE (Narrative) (Details) - USD ($) $ in Millions |
3 Months Ended | 6 Months Ended | ||||
|---|---|---|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Jun. 30, 2018 |
Jun. 30, 2017 |
Jan. 01, 2018 |
Dec. 31, 2017 |
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| Revenues | $ 714.3 | $ 471.3 | $ 894.3 | $ 757.5 | ||
| Deferred revenue, current | 20.0 | 20.0 | $ 23.8 | |||
| Deferred revenue, noncurrent | 47.1 | 47.1 | 51.4 | |||
| Other current liabilities | 66.2 | 66.2 | $ 68.8 | 67.4 | ||
| Customer Supplemental Payments [Member] | ||||||
| Deferred revenue | 59.9 | 59.9 | 64.2 | |||
| Deferred revenue, current | 12.8 | 12.8 | 12.8 | |||
| Take or Pay Contracts [Member] | ||||||
| Deferred revenue | 7.2 | 7.2 | $ 9.6 | |||
| U.S. Iron Ore [Member] | ||||||
| Revenues | 714.3 | 471.3 | 894.3 | 757.5 | ||
| Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | ||||||
| Revenues | 110.0 | 47.5 | ||||
| Other current liabilities | 5.9 | 5.9 | $ 1.4 | |||
| Not Designated as Hedging Instrument [Member] | ||||||
| Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net | $ 154.7 | $ 30.8 | $ 198.5 | $ 63.0 | ||
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- Definition Amount of deferred revenue as of balance sheet date. Deferred revenue represents collections of cash or other assets related to a revenue producing activity for which revenue has not yet been recognized. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The carrying amount of consideration received or receivable as of the balance sheet date on potential earnings that were not recognized as revenue in conformity with GAAP, and which are expected to be recognized as such within one year or the normal operating cycle, if longer, including sales, license fees, and royalties, but excluding interest income. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition The noncurrent portion of deferred revenue amount as of balance sheet date. Deferred revenue is a liability related to a revenue producing activity for which revenue has not yet been recognized, and is not expected to be recognized in the next twelve months. Generally, an entity records deferred revenue when it receives consideration from a customer before achieving certain criteria that must be met for revenue to be recognized in conformity with GAAP. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of liabilities classified as other, due within one year or the normal operating cycle, if longer. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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