Accrued Liabilities (Accrued Liabilities) (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Accrued Liabilities [Abstract]
Employee costs	$ 7,184	$ 8,878
Lease operating expenses	3,686	6,405
Capital expenditures	5,500	3,461
Taxes	5,352	2,324
Interest payable	303	884
Legal settlement	0	2,070
Other	1,723	1,182
Total accrued liabilities	$ 23,748	$ 25,204