Annual report pursuant to Section 13 and 15(d)

BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Investments In Unconsolidated Ventures) (Details)

v2.4.0.8
BASIS OF PRESENTATION AND SIGNIFICANT ACCOUNTING POLICIES (Investments In Unconsolidated Ventures) (Details)
12 Months Ended
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Dec. 31, 2011
USD ($)
Dec. 31, 2013
Asia Pacific Iron Ore [Member]
Facility
Dec. 31, 2012
Asia Pacific Iron Ore [Member]
Cockatoo [Member]
AUD
Dec. 31, 2013
Investments in Ventures [Member]
Amapa [Member]
Dec. 31, 2012
Investments in Ventures [Member]
Amapa [Member]
USD ($)
Dec. 31, 2013
Investments in Ventures [Member]
Hibbing [Member]
Dec. 31, 2013
Investments in Ventures [Member]
Other Equity Investees [Member]
USD ($)
Dec. 31, 2012
Investments in Ventures [Member]
Other Equity Investees [Member]
USD ($)
Dec. 31, 2013
Other Noncurrent Liabilities [Member]
Cockatoo [Member]
Dec. 31, 2012
Other Noncurrent Liabilities [Member]
Cockatoo [Member]
USD ($)
Dec. 31, 2013
Other Noncurrent Liabilities [Member]
Hibbing [Member]
USD ($)
Dec. 31, 2012
Other Noncurrent Liabilities [Member]
Hibbing [Member]
USD ($)
Schedule of Equity Method Investments [Line Items]                            
Ownership interest, equity method investment           0.00% [1] 30.00% [1] 23.00%     0.00% [2] 50.00% [2]    
Total percentage of Amapa sold           100.00%                
Investment $ 30,800,000 $ 108,400,000         $ 101,900,000 [1]   $ 34,700,000 $ 33,900,000   $ (25,300,000) [2] $ (3,900,000) $ (2,100,000)
Proceeds from sale of economic interest (in AUD)         4.00                  
Number Of Mines       1                    
Allowance for Doubtful Accounts Receivable 8,100,000 8,100,000                        
Provision for Doubtful Accounts $ 0 $ 9,000,000 $ 5,900,000                      
[1] At December 31, 2012, our ownership interest percentage for Amapá was 30 percent.
[2] At December 31, 2012, our ownership interest percentage for Cockatoo was 50 percent.