Inventory

12 Months Ended

Dec. 31, 2012

INVENTORY

2. INVENTORY

As of December 31, 2012, 78% of the Company's inventory was valued using average cost, 14% was determined using the FIFO method and the remaining inventory was valued using the specific identification method. The following table summarizes our inventory balances as of December 31, 2012 and 2011:

	2012		2011
	(in millions)
Coal, fuel oil and other raw materials	$	373	$	434
Spare parts and supplies		396		341
Total	$	769	$	775