Annual report pursuant to Section 13 and 15(d)

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

v3.6.0.2
GOODWILL AND OTHER INTANGIBLE ASSETS AND LIABILITIES (Narrative) (Details) - USD ($)
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Goodwill [Line Items]      
Goodwill, Impairment Loss $ 0 $ 0  
Product 1,913,500,000 1,832,400,000 $ 3,095,200,000
Cost of Sales [Member]      
Goodwill [Line Items]      
Amortization expense relating to intangible assets 4,800,000 4,200,000 8,400,000
Sales Revenue, Goods, Net [Member] | Sales Revenue, Goods, Net [Member]      
Goodwill [Line Items]      
Product 23,100,000 $ 23,100,000 23,100,000
Permits [Member]      
Goodwill [Line Items]      
Impairment of Intangible Assets, Finite-lived 0   13,800,000
Asia Pacific Iron Ore [Member]      
Goodwill [Line Items]      
Goodwill, Impairment Loss     $ 73,500,000
U.S. Iron Ore [Member]      
Goodwill [Line Items]      
Goodwill $ 2,000,000