Quarterly report pursuant to Section 13 or 15(d)

Revenue (Narrative) (Details)

v3.10.0.1
Revenue (Narrative) (Details)
$ in Millions
 6 Months Ended
Jun. 30, 2018
USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Initial crude oil sales and purchase agreement period 1 year
Interval period, between lifting 30 days
Monthly royalty rate, based on production at the published price 13.00%
Working interest of carried partner, percentage 7.50%
Foreign taxes payable attributable to sharing obligation $ 5.4
Maximum [Member]  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Lifting period, time to complete 2 days
Minimum [Member]  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Lifting period, time to complete 1 day