Annual report pursuant to Section 13 and 15(d)

ACQUISITIONS (Narrative) (Details)

v2.4.0.8
ACQUISITIONS (Narrative) (Details)
 3 Months Ended 12 Months Ended 12 Months Ended 3 Months Ended 3 Months Ended 3 Months Ended 12 Months Ended
Dec. 31, 2013
USD ($)
Sep. 30, 2013
USD ($)
Jun. 30, 2013
USD ($)
Mar. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Sep. 30, 2012
USD ($)
Jun. 30, 2012
USD ($)
Mar. 31, 2012
USD ($)
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Dec. 31, 2011
USD ($)
Dec. 31, 2013
Eastern Canadian Iron Ore [Member]
USD ($)
Dec. 31, 2012
Eastern Canadian Iron Ore [Member]
USD ($)
Dec. 31, 2011
Eastern Canadian Iron Ore [Member]
USD ($)
Dec. 31, 2012
Consolidated Thompson [Member]
USD ($)
Dec. 31, 2011
Consolidated Thompson [Member]
USD ($)
May 12, 2011
Consolidated Thompson [Member]
USD ($)
May 12, 2011
Consolidated Thompson [Member]
CAD
Dec. 31, 2011
Consolidated Thompson [Member]
Acquisition-related Costs [Member]
USD ($)
Dec. 31, 2011
Consolidated Thompson [Member]
Fair Value Adjustment to Inventory [Member]
USD ($)
Dec. 31, 2010
Consolidated Thompson [Member]
Fair Value Adjustment to Inventory [Member]
USD ($)
Jun. 30, 2011
Consolidated Thompson [Member]
Initial Allocation [Member]
USD ($)
May 12, 2011
Consolidated Thompson [Member]
Initial Allocation [Member]
USD ($)
Jun. 30, 2011
Consolidated Thompson [Member]
Final Allocation [Member]
USD ($)
Jun. 30, 2012
Consolidated Thompson [Member]
Final Allocation [Member]
USD ($)
Jun. 30, 2011
Consolidated Thompson [Member]
Change [Member]
USD ($)
Jun. 30, 2012
Consolidated Thompson [Member]
Change [Member]
USD ($)
Dec. 31, 2012
Consolidated Thompson [Member]
Eastern Canadian Iron Ore [Member]
USD ($)
Dec. 31, 2013
Wisco [Member]
Dec. 31, 2012
Wisco [Member]
Dec. 31, 2011
Interest Expense, Net [Member]
Consolidated Thompson [Member]
USD ($)
Dec. 31, 2011
Other Current Assets [Member]
Consolidated Thompson [Member]
USD ($)
Dec. 31, 2011
Other Non-current Assets [Member]
Consolidated Thompson [Member]
USD ($)
Business Acquisition [Line Items]                                                                  
Net income                 $ 361,800,000 $ (1,126,600,000) $ 1,812,600,000               $ 69,600,000 $ 59,800,000 $ 59,800,000                        
Cost per share acquired (in CAD per share)                                   17.25                              
Business Acquisition, Transaction Costs                                 4,600,000,000                                
Subsidiary Or Equity Method Investee Percentage Ownership Acquired                                                         17.152% 25.00%      
Pre-acquisition date Quebec mining duties tax                             16,400,000                                    
Increase in current liabilities                             6,100,000                                    
Increase in long-term liabilities                             10,300,000                                    
Reduction of calculated minimum distribution payable to the minority partner                             2,600,000                                    
Increase in goodwill                             13,800,000                                    
Noncontrolling interest in subsidiary                               1,075,400,000             947,600,000   1,075,400,000   127,800,000            
Acquisition-related costs                               25,400,000                                  
Deferred debt issuance costs                               15,700,000                               1,700,000 14,000,000
Deferred debt issuance costs, accumulated amortization                               1,900,000                                  
Write off of deferred debt issuance costs                                                             38,300,000    
Incremental revenue from business acquisition 1,515,800,000 1,546,600,000 1,488,500,000 1,140,500,000 1,535,900,000 1,544,900,000 1,579,500,000 1,212,400,000 5,691,400,000 5,872,700,000 6,563,900,000 978,700,000 1,008,900,000 1,178,100,000   571,000,000                                  
Incremental income from business acquisition                 671,000,000 (308,800,000) 2,296,800,000         143,700,000                                  
Stepped-up value of inventory and reserves due to purchase accounting                               59,800,000                                  
Cash portion of acquisition consideration                                           4,554,000,000   4,554,000,000   0              
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Mineral Rights                               4,825,600,000             4,450,000,000   4,825,600,000   375,600,000            
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Deferred Tax Liabilities Noncurrent                               1,041,800,000             (831,500,000)   (1,041,800,000)   (210,300,000)            
Goodwill $ 74,500,000       $ 167,400,000       $ 74,500,000 $ 167,400,000 $ 1,152,100,000 $ 0 $ 0 $ 986,200,000                 $ 1,026,800,000   $ 997,300,000   $ (29,500,000) $ 997,300,000