Quarterly report pursuant to Section 13 or 15(d)

SEGMENT REPORTING (Schedule Of Segment Reporting Information, By Segment) (Details)

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SEGMENT REPORTING (Schedule Of Segment Reporting Information, By Segment) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2014
Mar. 31, 2013
Segment Reporting Information [Line Items]    
Revenues from producet sales and services, percent 100.00% 100.00%
Revenues from product sales and services $ 940.0 $ 1,140.5
Sales Margin 63.2 237.9
Other operating expense (113.9) (69.6)
Other expense (41.5) (48.0)
Income from Continuing Operations before income taxes and equity (loss) from ventures (92.2) 120.3
Depreciation, depletion and amortization 141.1 140.6
Capital Additions 79.2 [1] 195.7 [1]
U.S. Iron Ore [Member]
    
Segment Reporting Information [Line Items]    
Revenues from producet sales and services, percent 38.00% 36.00%
Revenues from product sales and services 361.3 410.1
Sales Margin 95.0 157.3
Depreciation, depletion and amortization 28.7 26.6
Capital Additions 14.9 [1] 11.7 [1]
Eastern Canadian Iron Ore [Member]
    
Segment Reporting Information [Line Items]    
Revenues from producet sales and services, percent 17.00% 22.00%
Revenues from product sales and services 158.3 245.3
Sales Margin (49.7) 19.4
Depreciation, depletion and amortization 41.2 41.1
Capital Additions 51.0 [1] 167.0 [1]
Asia Pacific Iron Ore [Member]
    
Segment Reporting Information [Line Items]    
Revenues from producet sales and services, percent 27.00% 24.00%
Revenues from product sales and services 254.2 270.8
Sales Margin 66.3 61.3
Depreciation, depletion and amortization 39.1 36.4
Capital Additions 3.2 [1] 4.3 [1]
North American Coal [Member]
    
Segment Reporting Information [Line Items]    
Revenues from producet sales and services, percent 18.00% 18.00%
Revenues from product sales and services 166.2 214.3
Sales Margin (48.4) 1.8
Depreciation, depletion and amortization 29.9 32.5
Capital Additions 9.2 [1] 11.1 [1]
All Other Segments [Member]
    
Segment Reporting Information [Line Items]    
Sales Margin 0 (1.9)
Depreciation, depletion and amortization 2.2 4.0
Capital Additions $ 0.9 [1] $ 1.6 [1]
[1] Includes capital lease additions and non-cash accruals. Refer to NOTE 19 - CASH FLOW INFORMATION.