Commitments and Contingencies (Details) (USD $)	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Litigation [Abstract]
Arbitration award issued against KBR	$ 201,000,000
Environmental [Abstract]
Accrued liabilities for environmental matters		81,000,000	47,000,000
Number of superfund sites		9
Accrued liabilities for superfund sites		7,000,000
Leases [Abstract]
Rental expense, net of sublease rentals		735,000,000	591,000,000	528,000,000
Future rentals on noncancellable operating leases [Abstract]
2012		207,000,000
2013		166,000,000
2014		112,000,000
2015		87,000,000
2016		64,000,000
Thereafter		164,000,000
Financial agreements [Member]
Guarantee arrangements [Abstract]
Guarantee arrangements outstanding		1,700,000,000
Venezuela surety bonds [Member]
Guarantee arrangements [Abstract]
Guarantee arrangements outstanding		292,000,000
The Gulf of Mexico/Macondo well incident [Member]
Loss Contingencies [Line Items]
Federal government estimate of oil discharged from the well (in barrels)		4.9
Number of fatalities		11
Number Of Months That Settlement Activities Have Been Ongoing		9
Number of independent bureaus created to replace the Minerals Management Service		2
Number of parties-of-interest in the Marine Board investigation		16
Maximum per day assessment for negligent discharges under the CWA		50,000
Maximum per day assessment for knowing discharges under the CWA		100,000
Maximum per day assessment for negligent endangerment under the CWA		2,000,000
Maximum per barrel civil penalty for strict liability under the CWA		1,100
Maximum per barrel civil penalty for gross negligence under the CWA		4,300
Liability cap under the OPA in addition to the full cost of removal of the discharged oil		75,000,000
Maximum fine per bird killed under the MBTA		15,000
Maximum imprisonment under the MBTA (in months)		6
Maximum civil penalty per violation under the ESA		25,000
Maximum criminal penalty per violation under the ESA		50,000
Anadarko interest in Macondo well		25.00%
DOJ minimum estimate of removal costs and damages to the United Sates due to discharges of oil into the Gulf of Mexico		75,000,000
Number of days of advance notice to DOJ of any event that may involve substantial transfers of cash or other corporate assets outside the ordinary course of business (in days)		30
Number of key findings related to possible causes of the well incident		8
Number of safeguards that could have contained hydrocarbon pressures		3
Number of centralizers used by BP		6
Number of general root causes of the well incident identified by the Investigation Report		2
Number of pods with depleted battery		1
Number of cement barriers		1
Maximum per day fine for violating federal regulations related to INCs		35,000
Number Of Days To File Notice After Conclusion Of Mdl		15
Number of days to appeal INCs issued by the BSEE		60
Number of minutes taken to note loss of well control		50
Litigation [Abstract]
Minimum number of environmental class-action complaints		400
Minimum number of wrongful death and personal injury multiple plaintiff lawsuits		9
Number of decedents in personal injury lawsuits		4
Number of allegedly injured persons in personal injury lawsuits		21
Minimum number of lawsuits naming the company		6
Number of Louisiana lawsuits not consolidated		2
Number of Louisiana lawsuits not consolidated that are proceeding in Louisiana federal court		1
Number of Texas state court lawsuits not consolidated		2
Number Of Lawsuits In Florida State Court Not Yet Served		4
Number of lawsuits in Florida federal court not consolidated		2
Number of Mexican states included in pollution complaint		3
Number of Louisiana parishes included in pollution complaint		10
Number of proceedings treated as associated cases		2
Number Of Phases Involved In Limitation Action Trial		3
Interest of MOEX in Macondo well (in hundreths)		10.00%
Indemnification and insurance [Abstract]
Total amount of general liability insurance program		600,000,000
Pre-tax charge recognized by BP as a result of the Macondo well incident		40,000,000,000
Legal fees and related expenses covered by insurance		76,000,000
Barracuda-Caratinga arbitration [Member]
Litigation [Abstract]
Petrobras arbitration claim against KBR		220,000,000
Securities and related litigation [Member]
Litigation [Abstract]
Number of similar class action lawsuits that were later consolidated into one suit		20
Shareholder derivative cases [Member]
Litigation [Abstract]
Number of shareholder derivative lawsuits		2
Duncan, Oklahoma environmental matter [Member]
Environmental [Abstract]
Accrued liabilities for environmental matters		$ 35,000,000
Number Of Years Passed Since Alleged Release		25