Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Inventories [Abstract]

Inventory Amounts by Product Type

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

	December 31,
	2017		2016
NGLs	$	917.4	$	1,156.1
Petrochemicals and refined products		161.5		220.7
Crude oil		516.3		360.0
Natural gas		14.6		33.7
Total	$	1,609.8	$	1,770.5

Cost of Sales and Lower of Cost or Market Adjustments

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

	For the Year Ended December 31,
	2017		2016		2015
Cost of sales (1)	$	21,487.0	$	15,710.9	$	19,612.9
Lower of cost or net realizable value adjustments within cost of sales		9.1		11.5		19.8
(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.