Exploratory Well Costs (Tables)

12 Months Ended

Dec. 31, 2018

Extractive Industries [Abstract]

Capitalized exploratory well and project activity

Capitalized exploratory well project activity is as follows:

	Year Ended December 31,
	2018			2017			2016
	(in millions)
Beginning capitalized exploratory well costs	$	505		$	323		$	306
Additions to exploratory well costs pending the determination of proved reserves	2,585			1,956			1,387
Reclassification due to determination of proved reserves	(2,557		)	(1,764		)	(1,369		)
Disposition of assets	(1		)	—			—
Exploratory well costs charged to exploration and abandonment expense	(23		)	(10		)	(1		)
Ending capitalized exploratory well costs	$	509		$	505		$	323

Capitalized exploratory costs and the number of projects for which exploratory costs have been capitalized

Aging of capitalized exploratory costs and the number of projects for which exploratory well costs have been capitalized for a period greater than one year, based on the date drilling was completed are as follows:

	As of December 31,
	2018		2017		2016
	(in millions, except well counts)
Capitalized exploratory well costs that have been suspended:
One year or less	$	509	$	493	$	318
More than one year	—		12		5
	$	509	$	505	$	323
Number of projects with exploratory well costs that have been suspended for a period greater than one year	—		7		3