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Inventory
3 Months Ended
Jun. 30, 2011
INVENTORY

2. INVENTORY

The following table summarizes the Company's inventory balances as of June 30, 2011 and December 31, 2010:

  June 30, December 31,
  2011 2010
       
  (in millions)
Coal, fuel oil and other raw materials $ 351 $ 276
Spare parts and supplies   303   286
Total $ 654 $ 562