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.