Quarterly report pursuant to Section 13 or 15(d)

Revenue (Revenues from Contracts with Customers) (Details)

v3.19.3
Revenue (Revenues from Contracts with Customers) (Details) - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
Sep. 30, 2018
Sep. 30, 2019
Sep. 30, 2018
Disaggregation of Revenue [Line Items]        
Carried interest recoupment $ 511 $ 573 $ 1,951 $ 1,929
Royalties (2,568) (3,623) (9,120) (10,757)
Total revenue, net 17,603 25,266 62,598 77,337
Sales Under COSPA [Member]        
Disaggregation of Revenue [Line Items]        
Revenue from customer contracts $ 19,660 18,931 62,420 74,587
Gabonese Government Share Of Profit Oil [Member]        
Disaggregation of Revenue [Line Items]        
Revenue from customer contracts       2,193
Revenue not from customer contracts   $ 9,385 $ 7,347 $ 9,385