Asset Exchange Transactions and Divestiture (Details) $ in Thousands		3 Months Ended		6 Months Ended
	May 11, 2020 USD ($) well mi	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2020 USD ($) a	Dec. 31, 2020 USD ($)
Nonmonetary Transaction
Loss from asset exchange transaction		$ (16,816)	$ 49,207	$ (18,023)	$ 98,059
Derivative instruments, at fair value		2,160,253		2,160,253		$ 600,877
2020 Divestiture
Nonmonetary Transaction
Loss from asset exchange transaction			42,500
2020 Divestiture | Pennsylvania
Nonmonetary Transaction
Miles of gathering lines (in miles) | mi	33
2020 Divestiture | West Virginia
Nonmonetary Transaction
Miles of gathering lines (in miles) | mi	154
Disposal Group, Not Discontinued Operations | 2020 Divestiture
Nonmonetary Transaction
Purchase price	$ 125,000
Repayment of asset retirement obligation and other liabilities	$ 49,000
Potential contingent consideration		20,000		20,000
Derivative instruments, at fair value		$ 17,500		$ 17,500		$ 1,900
Disposal Group, Not Discontinued Operations | 2020 Divestiture | Pennsylvania
Nonmonetary Transaction
Number of wells sold | well	80
Disposal Group, Not Discontinued Operations | 2020 Divestiture | West Virginia
Nonmonetary Transaction
Number of wells sold | well	809
Asset Exchange Transaction
Nonmonetary Transaction
Area of acres exchanged (in acres) | a					11,700
Area of acres obtained in asset exchange (in acres) | a					11,700
Loss from asset exchange transaction			$ 6,700		$ 55,600