SEGMENT REPORTING (Narrative) (Details)	3 Months Ended
Mar. 31, 2013 Facility
U.S. Iron Ore [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	5
Eastern Canadian Iron Ore [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	2
North American Coal [Member] \| Metallurgical Coal Mines [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	6
North American Coal [Member] \| Thermal Coal Mines [Member]
Segment Reporting Information [Line Items]
Number of mines (in number of facilities)	1
Latin American Iron Ore [Member] \| Amapa [Member]
Segment Reporting Information [Line Items]
Interest Percentage	30.00%

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_EquityMethodInvestmentOwnershipPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant