Quarterly report pursuant to Section 13 or 15(d)

GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Narrative) (Details)

v3.4.0.3
GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Narrative) (Details) - USD ($)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2016
Mar. 31, 2015
Dec. 31, 2016
Goodwill [Line Items]      
Product $ 275.6 $ 399.5  
Cost of Sales [Member]      
Goodwill [Line Items]      
Amortization expense relating to intangible assets 1.4 $ 1.1  
Sales Revenue, Goods, Net [Member] | Sales Revenue, Goods, Net [Member]      
Goodwill [Line Items]      
Product 0.0    
U.S. Iron Ore [Member]      
Goodwill [Line Items]      
Goodwill $ 2.0    
Scenario, Forecast [Member]      
Goodwill [Line Items]      
Future Below Market Sales Contracts Revenue Year One     $ 23.1