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Commitments and Contingencies (Narrative) (Details) (USD $)
In Millions, unless otherwise specified |
6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 3 Months Ended | 6 Months Ended | 12 Months Ended | 6 Months Ended | 12 Months Ended | ||||||
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Jun. 30, 2011
MT
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Jun. 30, 2011
Bloom Lake [Member]
MT
|
Dec. 31, 2011
Bloom Lake [Member]
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Jun. 30, 2011
Lower War Eagle [Member]
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Dec. 31, 2011
Lower War Eagle [Member]
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Jun. 30, 2011
Koolyanobbing [Member]
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Dec. 31, 2012
Koolyanobbing [Member]
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Dec. 31, 2011
Koolyanobbing [Member]
|
Dec. 31, 2010
Koolyanobbing [Member]
MT
|
Jun. 30, 2011
Empire [Member]
T
|
Jun. 30, 2011
Empire and Tilden [Member]
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Dec. 31, 2012
Empire and Tilden [Member]
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Dec. 31, 2011
Empire and Tilden [Member]
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Jun. 30, 2011
Tilden [Member]
T
|
Jun. 30, 2011
Oak Grove [Member]
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Jun. 30, 2011
Oak Grove [Member]
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Dec. 31, 2011
Oak Grove [Member]
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Dec. 31, 2011
Oak Grove II [Member]
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Jun. 30, 2011
Pinnacle [Member]
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Dec. 31, 2011
Pinnacle [Member]
|
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| Capital investment committed | Ìý | $ 150 | Ìý | $ 31 | Ìý | $ 241 | Ìý | Ìý | Ìý | Ìý | $ 170 | Ìý | Ìý | Ìý | $ 31 | $ 31 | Ìý | Ìý | Ìý | Ìý |
| Increase in production capacity, tons | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 2,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Gross post-project production capacity, tons | 8,000,000 | 16,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | 11,000,000 | 3,000,000 | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý | Ìý |
| Capital investment paid | Ìý | 52 | Ìý | 8 | Ìý | 90 | Ìý | Ìý | Ìý | Ìý | 103 | Ìý | Ìý | Ìý | 6 | 20 | Ìý | Ìý | 89 | Ìý |
| Capital investment, future payments | Ìý | $ 615 | $ 98 | $ 49 | $ 23 | $ 280 | $ 21 | $ 130 | Ìý | Ìý | $ 325 | $ 17 | $ 50 | Ìý | $ 55 | $ 31 | $ 11 | $ 25 | $ 90 | $ 2 |