Quarterly report pursuant to Section 13 or 15(d)

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

v3.5.0.2
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