Cleveland-Cliffs Inc. Annual report pursuant to Section 13 and 15(d)

SEGMENT REPORTING (Narrative) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 customer	Dec. 31, 2011 customer	Dec. 31, 2010 customer
Sales Revenue, Net [Member] \| Customer Concentration Risk [Member]
Segment Reporting Information [Line Items]
Number of customers	1	1	3
Total revenue from customers that each individually accounted for more than 10 percent of consolidated product revenues	$ 923.7	$ 1,400.0	$ 1,800.0
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%
Sonoma [Member] \| Asia Pacific Coal [Member]
Segment Reporting Information [Line Items]
Ownership interest, percent	45.00%

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