Commitments and Contingencies (Details) (USD $)					3 Months Ended		3 Months Ended		3 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2012 Financial agreements [Member]	Mar. 31, 2012 Venezuela surety bonds [Member]	Mar. 31, 2012 Duncan, Oklahoma environmental matter [Member]	Mar. 31, 2012 Superfund sites [Member]	Mar. 31, 2012 The Gulf of Mexico/Macondo well incident [Member]	Apr. 18, 2012 The Gulf of Mexico/Macondo well incident [Member]	Sep. 30, 2011 Barracuda-Caratinga arbitration [Member]	Mar. 31, 2012 Barracuda-Caratinga arbitration [Member]	Mar. 31, 2012 Securities and related litigation [Member]	Mar. 31, 2012 Shareholder derivative cases [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 months that settlement activities have been ongoing (in months)							12
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 assessment for knowing 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 (in days)							15D
Number of days to appeal INCs issued by the BSEE (in days)							60D
Number of minutes taken to note loss of well control (in minutes)							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
The number of Louisiana lawsuits in state court related to the Macondo well incident that are not consolidated.							2
Number of Texas state court lawsuits not consolidated							1
Number Of Texas Federal Lawsuits Not Consolidated							1
Number of lawsuits in Florida federal court not consolidated							1
Number of lawsuits in Florida state court not yet served							4
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%
Petrobras arbitration claim against KBR										220,000,000
Arbitration award issued against KBR									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]
BPs estimated cost of settlement agreement with PSC							7,800,000,000
Number of settlement agreements								2
Pre-tax charge recognized by BP as a result of the Macondo well incident							40,000,000,000
Total amount of general liability insurance program							600,000,000
Legal fees and related expenses covered by insurance							100,000,000
Loss Contingency, Estimate of Probable Loss	300,000,000
Environmental [Abstract]
Accrued liabilities for environmental matters	79,000,000	81,000,000
Site Contingency [Line Items]
Number of years passed since alleged release (in years)					25
Number of superfund sites						10
Accrual for site contingency					32,000,000	6,000,000
Guarantee arrangements [Abstract]
Guarantee arrangements outstanding			$ 1,800,000,000	$ 292,000,000