Inventories (Tables)

12 Months Ended

Dec. 31, 2017

Energy Related Inventory [Abstract]

Inventory Disclosure Table

The following summarizes the major classes of inventories included in other current assets at December 31:

millions	2017		2016
Oil	$	165	$	169
Natural gas	29		38
NGLs	122		106
Total inventories	$	316	$	313