XML 102 R41.htm IDEA: XBRL DOCUMENT v2.4.0.6
Inventory (Tables)
12 Months Ended
Dec. 31, 2011
Inventory Tables [Abstract]  
Schedule of Inventory, Noncurrent [Table Text Block]
  December 31,
  2011 2010
       
  (in millions)
Coal, fuel oil and other raw materials $ 444 $ 272
Spare parts and supplies   341   277
Total $ 785 $ 549