|
Segment Reporting (Summary Of Assets By Segment) (Detail) (USD $)
In Millions, unless otherwise specified |
Jun. 30, 2012
|
Dec. 31, 2011
|
|---|---|---|
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | $ 15,194.3 | $ 14,541.7 |
|
U.S. Iron Ore [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | 1,915.4 | 1,691.8 |
|
Eastern Canadian Iron Ore [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | 8,138.3 | 7,973.1 |
|
North American Coal [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | 1,908.2 | 1,814.4 |
|
Asia Pacific Iron Ore [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | 1,859.4 | 1,511.2 |
|
Other Segment [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | 1,045.2 | 1,017.6 |
|
Total Segment Assets [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | 14,866.5 | 14,008.1 |
|
Corporate [Member]
|
Ìý | Ìý |
| Segment Reporting Information [Line Items] | Ìý | Ìý |
| Total assets | $ 327.8 | $ 533.6 |
| X | ||||||||||
|
- Definition
Sum of the carrying amounts as of the balance sheet date of all assets that are recognized. Assets are probable future economic benefits obtained or controlled by an entity as a result of past transactions or events. Reference 1: http://www.xbrl.org/2003/role/presentationRef
|
| X | ||||||||||
|
- Details
|