Revenue Recognition (Disaggregation of Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation of Revenue [Line Items]
Revenues	$ 300,661	$ 117,381	$ 551,460	$ 358,754
Oil sales
Disaggregation of Revenue [Line Items]
Revenues	280,577	108,538	513,621	337,115
Natural gas sales
Disaggregation of Revenue [Line Items]
Revenues	2,131	849	4,532	1,896
CO2 sales and transportation fees
Disaggregation of Revenue [Line Items]
Revenues	10,134	6,504	19,362	14,532
Oil marketing revenues
Disaggregation of Revenue [Line Items]
Revenues	$ 7,819	$ 1,490	$ 13,945	$ 5,211