Quarterly report pursuant to Section 13 or 15(d)

Commitments and Contingencies (Narrative) (Details)

 v2.3.0.11
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
Jun. 30, 2011
MT
Jun. 30, 2011
Bloom Lake [Member]
MT
Dec. 31, 2011
Bloom Lake [Member]
Jun. 30, 2011
Lower War Eagle [Member]
Dec. 31, 2011
Lower War Eagle [Member]
Jun. 30, 2011
Koolyanobbing [Member]
Dec. 31, 2012
Koolyanobbing [Member]
Dec. 31, 2011
Koolyanobbing [Member]
Dec. 31, 2010
Koolyanobbing [Member]
MT
Jun. 30, 2011
Empire [Member]
T
Jun. 30, 2011
Empire and Tilden [Member]
Dec. 31, 2012
Empire and Tilden [Member]
Dec. 31, 2011
Empire and Tilden [Member]
Jun. 30, 2011
Tilden [Member]
T
Jun. 30, 2011
Oak Grove [Member]
Jun. 30, 2011
Oak Grove [Member]
Dec. 31, 2011
Oak Grove [Member]
Dec. 31, 2011
Oak Grove II [Member]
Jun. 30, 2011
Pinnacle [Member]
Dec. 31, 2011
Pinnacle [Member]
Capital investment committed   $ 150   $ 31   $ 241         $ 170       $ 31 $ 31        
Increase in production capacity, tons                           2,000,000            
Gross post-project production capacity, tons 8,000,000 16,000,000             11,000,000 3,000,000                    
Capital investment paid   52   8   90         103       6 20     89  
Capital investment, future payments   $ 615 $ 98 $ 49 $ 23 $ 280 $ 21 $ 130     $ 325 $ 17 $ 50   $ 55 $ 31 $ 11 $ 25 $ 90 $ 2