Summary of Significant Accounting Policies Summary of Significant Accounting Policies - Disaggregated Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 221,825	$ 264,498	$ 593,529	$ 715,218
Lease bonus - mineral acreage	0	1,711	4,062	1,711
Realized (loss) gain on derivatives	(5,406)	3,346	49,571	7,781
Unrealized (loss) gain on derivatives	(13,033)	9,847	(9,271)	(29,715)
Total revenue	203,386	279,402	637,891	694,995
Oil revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	150,620	198,302	414,379	541,590
Natural gas revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	38,484	31,075	91,406	92,116
Third-party midstream services revenues
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	19,363	15,257	49,861	41,454
Sales of purchased natural gas
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	13,358	19,864	37,883	40,058
Total revenues from contracts with customers
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 221,825	$ 264,498	$ 593,529	$ 715,218