Quarterly report pursuant to Section 13 or 15(d)

Organization and Accounting Policies (Reconciliation of Cash, Cash Equivalents, and Restricted Cash) (Details)

v3.21.2
Organization and Accounting Policies (Reconciliation of Cash, Cash Equivalents, and Restricted Cash) (Details) - USD ($)
$ in Thousands
Jun. 30, 2021
Dec. 31, 2020
Jun. 30, 2020
Dec. 31, 2019
Organization and Accounting Policies [Abstract]        
Cash and cash equivalents $ 22,884 $ 47,853 $ 44,841  
Restricted cash - current 83 86 1,090  
Restricted cash - non-current 1,752 925 925  
Abandonment funding 22,837 12,453 11,420  
Total cash, cash equivalents and restricted cash $ 47,556 $ 61,317 $ 58,276 $ 59,124