Note 3. Inventories

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

	September 30, 2016		December 31, 2015
NGLs	$	1,202.4	$	639.9
Petrochemicals and refined products		230.4		148.0
Crude oil		299.3		222.1
Natural gas		30.4		28.1
Total	$	1,762.5	$	1,038.1

Our inventories, and associated working capital commitments, have increased significantly since December 31, 2015 primarily due to our marketing groups taking advantage of contango opportunities using our storage assets. We expect to gradually settle these inventory positions (valued at approximately $1 billion) through the first quarter of 2017, with a corresponding decrease in working capital commitments and related debt.

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. 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,
	2016		2015		2016		2015
Cost of sales (1)	$	4,088.6	$	4,419.9	$	11,135.6	$	15,355.9
Lower of cost or market adjustments within cost of sales		1.5		2.1		7.6		6.1

(1)Cost of sales is a component of “Operating costs and expenses” as presented on our Unaudited Condensed 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.