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GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Narrative) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | 12 Months Ended
--- | --- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015 | Dec. 31, 2016
Goodwill [Line Items] |  |  |  |  |
Product | $ 508.6 | $ 542.5 | $ 1,237.0 | $ 1,399.9 |
Cost of Sales [Member] |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Amortization expense relating to intangible assets | 1.2 | 0.9 | 3.8 | 3.1 |
Sales Revenue, Goods, Net [Member] | Sales Revenue, Goods, Net [Member] |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Product | 7.7 | $ 7.7 | 15.4 | $ 15.4 |
U.S. Iron Ore [Member] |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Goodwill | $ 2.0 |  | $ 2.0 |  |
Scenario, Forecast [Member] |  |  |  |  |
Goodwill [Line Items] |  |  |  |  |
Future Below Market Sales Contracts Revenue Year One |  |  |  |  | $ 7.7

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