Commitments and Contingencies (Details) (USD $)	1 Months Ended	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended					1 Months Ended
	Sep. 30, 2014 number_of_parts_within_secondphase_ofMDLtrial number_of_paymentinstallments	Sep. 30, 2014 number_of_parts_within_secondphase_ofMDLtrial number_of_paymentinstallments	Sep. 30, 2013	Sep. 30, 2014 number_of_parts_within_secondphase_ofMDLtrial number_of_paymentinstallments	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Macondo well incident bbl Phases Test_Cases Allegedly_Injured_Persons Complaints Personal_Injury_Lawsuits Decendents	Sep. 30, 2013 Macondo well incident	Sep. 30, 2014 Macondo well incident Phases Test_Cases Allegedly_Injured_Persons Complaints Personal_Injury_Lawsuits Decendents	Jun. 30, 2014 Macondo well incident	Dec. 15, 2010 Macondo well incident	Apr. 22, 2010 Macondo well incident Fatalities	Sep. 30, 2014 Securities and related litigation Class_Actions	Jan. 31, 2013 Transocean [Member] Macondo well incident	Nov. 30, 2012 British Petroleum Exploration [Member] Macondo well incident Criminal_Charge
Loss Contingencies [Line Items]
Loss contingency related to Macondo well incident (non-current)	$ 805,000,000	$ 805,000,000		$ 805,000,000		$ 1,022,000,000
Loss contingency related to Macondo well (total)							1,200,000,000		1,200,000,000	1,300,000,000
Loss Contingency, Estimate of Possible Loss	72,000,000	72,000,000		72,000,000
Insurance Recoveries		95,000,000
Gain Contingency, Description		200
Loss Contingency, Loss in Period		(195,000,000)
Loss contingency related to Macondo well (current)	395,000,000	395,000,000		395,000,000		278,000,000
Federal government estimate of oil discharged from the well (in barrels)							4,200,000
Number of fatalities												11
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 civil penalty per violation under the ESA							25,000
Anadarko interest in Macondo well											25.00%
DOJ minimum estimate of removal costs and damages to the United States due to discharges of oil into the Gulf of Mexico							75,000,000
Loss Contingency Number Of Criminal Charges Plead Guilty															14
Loss Contingency Criminal Charges On Negligent Misinterpretation Of Negative Pressure Test Plead Guilty															13
Loss Contingency, Settlement Agreement, Consideration														1,000,000,000	4,000,000,000
Loss Contingency, Damages Paid, Value														0	1,300,000,000
Loss Contingency Drilling Probation Term								3 years							5 years
Maximum per day fine for violating federal regulations related to INCs							35,000
Loss Contingency, Information about Litigation Matters [Abstract]
Minimum number of environmental class-action complaints							1,800		1,800
Criminal Fines, DOJ Macondo Settlement			200,000
Minimum number of wrongful death and personal injury multiple plaintiff lawsuits							6		6
Number of decedents in personal injury lawsuits							3		3
Number of allegedly injured persons in personal injury lawsuits							2		2
Minimum number of lawsuits naming the company							6		6
Number Of Phases Involved In Limitation Action Trial							2		2
Number of OPA Test Cases							7		7
Number of similar class action lawsuits that were later consolidated into one suit													20
Loss Contingency, Settlement Agreement, Terms	1,100,000,000			0	219,000,000
Number of Payment Installments	3	3		3
Installment Payment for Legal Fees	1	1		1
Liability for compensatory damages to the class members of the BP Economic Loss settlement related to the final order of the MDL court	0	0		0
BP Fault Apportionment in Macondo Ruling	0.00%	0.00%		0.00%
Transocean Fault Apportionment In Macondo Ruling	0.00%	0.00%		0.00%
Halliburton Fault Apportionment In Macondo Ruling	0.00%	0.00%		0.00%
Number of Parts within Second Phase of MDL trial	2	2		2
Number Of Years	2 years
BP Estimate Of Amount Of Oil Discharged							2,450,000
Indemnification and insurance [Abstract]
Total amount of general liability insurance program							600,000,000		600,000,000
Legal Fees									312,000,000
Legal fees and related expenses covered by insurance							$ 276,000,000		$ 276,000,000
Number Of Days To Appeal Incs Issued By Bsee							60 days