Note 4. Inventories

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

	December 31,
	2016		2015
NGLs	$	1,156.1	$	639.9
Petrochemicals and refined products		220.7		148.0
Crude oil		360.0		222.1
Natural gas		33.7		28.1
Total	$	1,770.5	$	1,038.1

Our inventories, and associated working capital commitments, increased significantly during 2016 primarily due to our marketing groups utilization of contango opportunities using our storage assets. We expect to gradually settle these inventory positions (valued at approximately $1.1 billion) through the first quarter of 2017, with a corresponding decrease in working capital commitments and related debt.

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.

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

	For the Year Ended December 31,
	2016			2015			2014
Cost of sales (1)		$	15,710.9		$	19,612.9		$	40,464.1
Lower of cost or market adjustments within cost of sales			11.5			19.8			22.8
(1) Cost of sales is a component of “Operating costs and expenses,” as presented on our Statements of Consolidated Operations. Fluctuations in these amounts are primarily due to changes in energy commodity prices and sales volumes associated with our marketing activities.

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 14 for a description of our commodity hedging activities.