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 6 Months Ended 12 Months Ended
Jun. 30, 2016
Jun. 30, 2015
Jun. 30, 2016
Jun. 30, 2015
Dec. 31, 2016
Goodwill [Line Items]          
Product $ 452.8 $ 454.3 $ 728.4 $ 857.4  
Cost of Sales [Member]          
Goodwill [Line Items]          
Amortization expense relating to intangible assets 1.2 1.0 2.6 2.1  
Sales Revenue, Goods, Net [Member] | Sales Revenue, Goods, Net [Member]          
Goodwill [Line Items]          
Product 7.7 $ 7.7 7.7 $ 7.7  
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         $ 15.4