Quarterly report pursuant to Section 13 or 15(d)

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

v2.4.0.6
Segment Reporting (Schedule Of Segment Reporting Information, By Segment) (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Segment Reporting Information [Line Items]    
Revenues from product sales and services for reportable segments, percent 100.00% 100.00%
Revenues from product sales and services $ 1,264.7 $ 1,183.2
Sales margin 303.5 599.5
Other operating expense (72.4) (57.4)
Other income (expense) (43.5) 20.9
INCOME FROM CONTINUING OPERATIONS BEFORE INCOME TAXES AND EQUITY INCOME (LOSS) FROM VENTURES 187.6 563.0
Depreciation, depletion and amortization 117.3 79.8
Capital additions 353.4 [1] 91.0 [1]
U.S. Iron Ore [Member]
    
Segment Reporting Information [Line Items]    
Revenues from product sales and services for reportable segments, percent 35.00% 43.00%
Revenues from product sales and services 441.7 510.2
Sales margin 166.9 361.3
Depreciation, depletion and amortization 23.2 17.5
Capital additions 34.8 [1] 31.6 [1]
Eastern Canadian Iron Ore [Member]
    
Segment Reporting Information [Line Items]    
Revenues from product sales and services for reportable segments, percent 18.00% 11.00%
Revenues from product sales and services 220.7 127.3
Sales margin (14.3) 34.5
Depreciation, depletion and amortization 37.9 9.6
Capital additions 130.6 [1] 3.5 [1]
North American Coal [Member]
    
Segment Reporting Information [Line Items]    
Revenues from product sales and services for reportable segments, percent 15.00% 14.00%
Revenues from product sales and services 189.9 165.0
Sales margin 14.5 (2.9)
Depreciation, depletion and amortization 20.1 21.6
Capital additions 39.1 [1] 27.5 [1]
Asia Pacific Iron Ore [Member]
    
Segment Reporting Information [Line Items]    
Revenues from product sales and services for reportable segments, percent 28.00% 29.00%
Revenues from product sales and services 359.8 345.4
Sales margin 125.0 195.8
Depreciation, depletion and amortization 30.0 24.0
Capital additions 109.3 [1] 25.3 [1]
Other Segment [Member]
    
Segment Reporting Information [Line Items]    
Revenues from product sales and services for reportable segments, percent 4.00% 3.00%
Revenues from product sales and services 52.6 35.3
Sales margin 11.4 10.8
Depreciation, depletion and amortization 6.1 7.1
Capital additions $ 39.6 [1] $ 3.1 [1]
[1] Includes capital lease additions and non-cash accruals.