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