Note 5. Inventories

Our inventory amounts by product type were as follows at the dates indicated:

	March 31, 2012		December 31, 2011
NGLs	$	402.7	$	563.6
Petrochemicals and refined products		433.4		443.4
Crude oil		58.7		39.2
Natural gas		39.3		65.5
Total	$	934.1	$	1,111.7

In those instances where we take ownership of inventory volumes through percent-of-liquids contracts and similar arrangements (as opposed to actually purchasing volumes for cash from third parties), 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 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 summarizes our cost of sales and lower of cost or market adjustments for the periods presented:

	For the Three Months Ended March 31,
	2012		2011
Cost of sales (1)	$	9,665.8	$	8,819.3
Lower of cost or market adjustments		5.9		1.2
(1) Cost of sales is a component of "Operating costs and expenses," as presented on our Unaudited Condensed Statements of Consolidated Operations. Quarter-to-quarter fluctuations in these amounts are primarily due to changes in energy commodity prices and sales volumes associated with our marketing activities.