Commitments and Contingencies (Details) (USD $)	1 Months Ended		3 Months Ended
	Jan. 31, 2015 bbl	Sep. 30, 2014	Mar. 31, 2015 number_of_paymentinstallments	Mar. 31, 2014	Dec. 31, 2014	Dec. 15, 2010	Apr. 22, 2010 Fatalities
Loss Contingencies [Line Items]
Loss contingency related to Macondo well incident (non-current)			$ 439,000,000		$ 439,000,000
Loss contingency related to MDL Settlement			733,000,000
Loss Contingency, Estimate of Possible Loss			72,000,000
Insurance Recoveries			93,000,000
Gain Contingency, Description			200,000,000
Loss Contingency, Estimated Recovery from Third Party			170,000,000
Loss contingency related to Macondo well (current)			367,000,000		367,000,000
MDL Court Estimate of Amount of Oil Discharged	3.19
Loss Contingency, Information about Litigation Matters [Abstract]
Criminal Fines, DOJ Macondo Settlement				200,000
Loss Contingency, Settlement Agreement, Terms		1,100,000,000
Number of Payment Installments			3
Installment Payment for Legal Fees			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
BP Fault Apportionment in Macondo Ruling			0.00%
Transocean Fault Apportionment In Macondo Ruling			0.00%
Halliburton Fault Apportionment In Macondo Ruling			0.00%
Number Of Years		2 years
Macondo well incident
Loss Contingencies [Line Items]
Loss contingency related to Macondo well (total)			805,000,000
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 Drilling Probation Term				3 years
Maximum per day fine for violating federal regulations related to INCs			35,000
Loss Contingency, Information about Litigation Matters [Abstract]
Number of OPA Test Cases			7
Indemnification and insurance [Abstract]
Total amount of general liability insurance program			600,000,000
Legal Fees			322,000,000
Legal fees and related expenses covered by insurance			$ 283,000,000
Securities and related litigation
Loss Contingency, Information about Litigation Matters [Abstract]
Number of similar class action lawsuits that were later consolidated into one suit			20