Note 5. Inventories

Our available-for-sale inventory amounts by product type were as follows at the dates indicated:

	September 30, 2012		December 31, 2011
NGLs	$	702.5	$	563.6
Petrochemicals and refined products		246.9		443.4
Crude oil		57.5		39.2
Natural gas		62.3		65.5
Total	$	1,069.2	$	1,111.7

In those instances where we take ownership of inventory volumes through percent-of-liquids contracts and similar arrangements (as opposed to outright purchases from third parties for cash), these volumes are valued at market-based prices during the month in which they are acquired.

Due to fluctuating commodity prices, we recognize lower of cost or market adjustments when the carrying value of our available-for-sale inventories exceeds their net realizable value. These non-cash charges are a component of cost of sales in the period they are recognized. To the extent our commodity hedging strategies address inventory-related price risks and are successful, these inventory valuation adjustments are mitigated or offset. See Note 4 for a description of our commodity hedging activities.

The following table presents our total cost of sales amounts and lower of cost or market adjustments for the periods indicated:

	For the Three Months Ended September 30,				For the Nine Months Ended September 30,
	2012		2011		2012		2011
Cost of sales (1)	$	8,794.0	$	9,787.6	$	26,655.0	$	28,397.2
Lower of cost or market adjustments		2.2		5.1		16.1		6.8
(1) Cost of sales is a component of "Operating costs and expenses," as presented on our Unaudited Condensed Statements of Consolidated Operations. Period-to-period fluctuations in these amounts are primarily due to changes in energy commodity prices and sales volumes associated with our marketing activities.