Property, Plant and Equipment (Tables)

6 Months Ended

Jun. 30, 2018

Property Plant And Equipment [Abstract]

Net Changes in Capitalized Exploratory Well Costs

Capitalized Exploratory Well Costs:  The following table discloses the net changes in capitalized exploratory well costs pending determination of proved reserves during the six months ended June 30, 2018 (in millions):

Balance at January 1, 2018	$	304
Additions to capitalized exploratory well costs pending the determination of proved reserves		127
Balance at June 30, 2018	$	431