Annual report pursuant to Section 13 and 15(d)

COMMITMENTS AND CONTINGENCIES (Details)

v3.8.0.1
COMMITMENTS AND CONTINGENCIES (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Loss Contingencies [Line Items]      
Loans to and accounts receivables from the Canadian Entities $ 51.6 $ 48.6  
Contingent claims 55.6 0.0  
Short-term loan receivable 7.7    
LOSS FROM DISCONTINUED OPERATIONS, net of tax (18.7) (19.9) $ (892.1)
Accrual for Environmental Loss Contingencies 2.9 2.8  
Michigan Electricity Matters [Member]      
Loss Contingencies [Line Items]      
Loss Contingency Accrual 12.3 $ 13.6  
Wabush Scully Mine Sale [Member]      
Loss Contingencies [Line Items]      
LOSS FROM DISCONTINUED OPERATIONS, net of tax $ 31.4