Annual report pursuant to Section 13 and 15(d)

DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Income Statement, Balance Sheet and Cash Flows (Details)

v3.3.1.900
DISCONTINUED OPERATIONS Schedule of Disposal Groups, including Discontinued Operations, Income Statement, Balance Sheet and Cash Flows (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Jul. 10, 2012
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
LOSS FROM DISCONTINUED OPERATIONS, net of tax $ (892.1) $ (8,368.0) $ (517.1)  
Income (Loss) from Discontinued Operations, net of tax, including portion attributable to Noncontrolling interest, Canadian Entities and North American Coal [1]     (519.1)  
Short-term assets of discontinued operations 14.9 326.9    
Long-term assets of discontinued operations 0.0 383.0    
Short-term liabilities of discontinued operations 6.9 399.4    
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS 0.0 427.5    
Depreciation, depletion and amortization 134.0 504.0 593.3  
Payments to Acquire Property, Plant, and Equipment 80.8 284.1 861.6  
Impairment of goodwill and other long-lived assets 76.6 9,029.9 250.8  
North American Coal [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
LOSS FROM DISCONTINUED OPERATIONS, net of tax (152.4) (1,134.5) (9.3)  
Short-term assets of discontinued operations 14.9 140.1    
Long-term assets of discontinued operations 0.0 113.3    
Short-term liabilities of discontinued operations 6.9 80.1    
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS 0.0 117.3    
Depreciation, depletion and amortization 3.2 106.9 128.9  
Payments to Acquire Property, Plant, and Equipment 15.9 29.9 64.1  
Impairment of goodwill and other long-lived assets 73.4 857.5 0.0  
Eastern Canadian Iron Ore [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
LOSS FROM DISCONTINUED OPERATIONS, net of tax (638.7) (6,952.9) (370.4)  
Short-term assets of discontinued operations 0.0 183.5    
Long-term assets of discontinued operations 0.0 256.0    
Short-term liabilities of discontinued operations 0.0 316.3    
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS 0.0 304.6    
Depreciation, depletion and amortization 0.0 135.6 178.6  
Payments to Acquire Property, Plant, and Equipment 0.0 190.3 718.3  
Impairment of goodwill and other long-lived assets 0.0 7,269.2 154.6  
Other Canadian Operations [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
LOSS FROM DISCONTINUED OPERATIONS, net of tax (101.0) (280.6) (139.4)  
Short-term assets of discontinued operations 0.0 3.3    
Long-term assets of discontinued operations 0.0 13.7    
Short-term liabilities of discontinued operations 0.0 3.0    
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS 0.0 5.6    
Depreciation, depletion and amortization 0.0 0.5 1.0  
Payments to Acquire Property, Plant, and Equipment 0.0 0.0 1.0  
Impairment of goodwill and other long-lived assets 0.0 267.6 81.8  
Canadian Entities [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
LOSS FROM DISCONTINUED OPERATIONS, net of tax (739.7) (7,233.5) (509.8)  
Short-term assets of discontinued operations 0.0 186.8    
Long-term assets of discontinued operations 0.0 269.7    
Short-term liabilities of discontinued operations 0.0 319.3    
LONG-TERM LIABILITIES OF DISCONTINUED OPERATIONS 0.0 310.2    
Depreciation, depletion and amortization 0.0 136.1 179.6  
Payments to Acquire Property, Plant, and Equipment 0.0 190.3 719.3  
Impairment of goodwill and other long-lived assets 0.0 7,536.8 236.4  
Discontinued Operations [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Depreciation, depletion and amortization 3.2 243.0 308.5  
Payments to Acquire Property, Plant, and Equipment 15.9 220.2 783.4  
Impairment of goodwill and other long-lived assets $ 73.4 $ 8,394.3 236.4  
Sonoma [Member] | Asia Pacific Coal [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Ownership Interest       45.00%
Income (Loss) From Discontinued Operations [Member] | Sonoma [Member]        
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]        
Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax     $ 2.0  
[1] Loss from Discontinued Operations, net of tax during the year end December 31, 2013 also includes an additional income tax benefit of $2.0 million resulting from the actual tax gain from the Sale of Sonoma as included in the 2012 tax return, which was filed during the year ended December 31, 2013. During the fourth quarter of 2012, we sold our 45 percent economic interest in Sonoma. The Sonoma operations previously were included in Other within our reportable segments.