Annual report pursuant to Section 13 and 15(d)

Acquisitions And Dispositions (Narrative) (Details)

v3.8.0.1
Acquisitions And Dispositions (Narrative) (Details)
$ in Thousands, a in Millions
 1 Months Ended 12 Months Ended
Nov. 22, 2016
Mar. 14, 2016
USD ($)
Jan. 01, 2014
Apr. 30, 2017
USD ($)
Dec. 31, 2016
USD ($)
item
Oct. 31, 2014
item
Nov. 30, 2006
a
item
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Dec. 31, 2015
USD ($)
Apr. 30, 2014
USD ($)
Business Acquisition [Line Items]                      
Proceeds from the sale of oil and gas properties               $ 250 $ 830 $ 398  
Gain from sale of property               300      
Allowance for accounts with partners         $ 500     $ 500 500    
Offshore Gabon [Member]                      
Business Acquisition [Line Items]                      
Production license agreement term extended by government               5 years      
Hefley Field [Member]                      
Business Acquisition [Line Items]                      
Proceeds received from sale of property         $ 800            
Number of wells, interest for sale | item         2            
East Poplar Dome Field [Member]                      
Business Acquisition [Line Items]                      
Proceeds from the sale of oil and gas properties       $ 300              
Joint Operating With Republic Of Angola [Member]                      
Business Acquisition [Line Items]                      
Primary term of the production sharing contract               4 years      
Optional term of extension of production sharing contract               3 years      
Area under acquire property exploration rights agreement term (acres) | a             1.4        
Number of exploration wells | item             2        
Number Of Additional Exploration Wells | item           2          
Joint operation agreement related to third party in working interest percentage             40.00%        
Additional joint operation agreement related to third party in working interest percentage             10.00%        
Stipulated payment for each exploration well, under PSA terms               $ 10,000      
Drilling commitment, net               5,000      
Liability for the penalty         $ 15,000     $ 15,000 15,000    
Allowance for accounts with partners                     $ 7,600
Working interest ownership other, percentage     40.00%                
Sojitz [Member]                      
Business Acquisition [Line Items]                      
Percentage of working interest 2.98%                    
Percentage of participating interest 3.23%                    
Actual impact on revenue from acquisition                 $ 200    
Sonangol P&P [Member]                      
Business Acquisition [Line Items]                      
Payment from joint venture partners   $ 19,000                  
Reversal of allowance   7,600                  
Interest income   $ 3,200