Litigation (Details) (Pending Litigation [Member], USD $)	1 Months Ended		9 Months Ended
	Sep. 30, 2010	Aug. 31, 2010	Sep. 30, 2012 LegalMatter	Feb. 14, 2011	Dec. 31, 2008
MTBE [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims)			7
Ecuador [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims)			9
Litigation (Textual) [Abstract]
Conducted remediation program (in years)			3 years
Remediation program			$ 40,000,000
Financial compensation for purported damages on mining engineer's report					18,900,000,000
Assessment for purported unjust enrichment on mining engineer's report					8,400,000,000
Court order requiring the parties to provide their positions on damages within (in days)		45 days
Approximate damages on plaintiffs' submission, Minimum	16,000,000,000
Approximate damages on plaintiffs' submission, Maximum	76,000,000,000
Approximate unjust enrichment on plaintiffs' submission, Minimum	5,000,000,000
Approximate unjust enrichment on plaintiffs' submission, Maximum	38,000,000,000
Amount assessed in damages				8,600,000,000
Amount assessed for plaintiffs representatives				900,000,000
Additional amount assessed in punitive damages				$ 8,600,000,000
Public apology date within judgment/clarification ruling (in days)				15 days
Proposed additional payment for plaintiff attorney fees as percentage of judgment			0.10%
Ecuador [Member] | Declatory Relief Claim [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims)			1
Ecuador [Member] | Discovery Stay On Claims [Member]
Loss Contingencies [Line Items]
Pending lawsuits and claims (in number of claims)			8