Commitments and Contingencies (Details) (USD $)	3 Months Ended		9 Months Ended	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Sep. 30, 2011 The Gulf of Mexico/Macondo well incident [Member]	Sep. 30, 2011 Barracuda-Caratinga arbitration [Member]	Sep. 30, 2011 Securities and related litigation [Member]	Sep. 30, 2011 Shareholder derivative cases [Member]	Sep. 30, 2011 Financial agreements [Member]	Sep. 30, 2011 Venezuela surety bonds [Member]
Loss Contingencies [Line Items]
Federal government estimate of oil discharged from the well (in barrels)			4,900,000
Number of fatalities			11
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)			6M
Maximum civil penalty per violation under the ESA			25,000
Maximum criminal penalty per violation under the ESA			50,000
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)			30D
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 cement barriers			1
Number of days to appeal INCs issued by the BSEE			60
Maximum per day fine for violating federal regulations related to INCs			35,000
Litigation [Abstract]
Minimum number of environmental class-action complaints			400
Minimum number of wrongful death and personal injury multiple plaintiff lawsuits			40
Number of decedents in personal injury lawsuits			7
Number of allegedly injured persons in personal injury lawsuits			59
Minimum number of lawsuits naming the company			6
Number of Louisiana lawsuits not consolidated			1
Number of Texas state court lawsuits not consolidated			3
Number of lawsuits in Florida federal court not consolidated			3
Number of Mexican states included in pollution complaint			3
Number of proceedings treated as associated cases			2
Interest of MOEX in Macondo well (in hundreths)			10.00%
Petrobras arbitration claim against KBR				220,000,000
Arbitration award issued against KBR	201,000,000			201,000,000
Number of similar class action lawsuits that were later consolidated into one suit					20
Number of shareholder derivative lawsuits						2
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			40,700,000,000
Environmental [Abstract]
Accrued liabilities for environmental matters	58,000,000	47,000,000
Number of superfund sites	10
Accrued liabilities for superfund sites	7,000,000
Guarantee arrangements [Abstract]
Guarantee arrangements outstanding							$ 1,600,000,000	$ 276,000,000