Litigation (Details) $ in Millions				1 Months Ended		12 Months Ended
	Nov. 13, 2013 USD ($)	Aug. 03, 2012 USD ($)	Feb. 14, 2011 USD ($)	Sep. 30, 2010 USD ($)	Aug. 31, 2010	Dec. 31, 1991 USD ($)	Dec. 31, 2017 LegalMatter	Nov. 06, 2012	Jan. 03, 2012	Dec. 31, 2008 USD ($)
MTBE | Pending Litigation
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims) | LegalMatter							8
Ecuador Litigation | Pending Litigation
Loss Contingencies [Line Items]
Remediation program term (in years)						3 years
Remediation program						$ 40
Financial compensation for purported damages on mining engineer's report										$ 18,900
Assessment for purported unjust enrichment on mining engineer's report										$ 8,400
Court order requiring the parties to provide their positions on damages within (in days)					45 days
Damages awarded	$ 9,500		$ 8,600
Additional amount assessed in punitive damages			8,600
Amount assessed for plaintiffs representatives			$ 900
Proposed additional payment for plaintiff attorney fees as percentage of judgment									0.10%
Public apology date within judgment			15 days
Amount awarded to other party		$ 19,100
Percentage of payments withheld by third parties due to freeze order (percent)								40.00%
Percentage of funds wIthheld by banks due to freeze order (percent)								40.00%
Ecuador Litigation | Pending Litigation | Minimum
Loss Contingencies [Line Items]
Estimate of possible loss				$ 16,000
Approximate unjust enrichment				5,000
Ecuador Litigation | Pending Litigation | Maximum
Loss Contingencies [Line Items]
Estimate of possible loss				76,000
Approximate unjust enrichment				$ 38,000
Ecuador Litigation | Declaratory Relief Claim
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims) | LegalMatter							1