Revolving Credit Facilities (Details)	1 Months Ended		6 Months Ended
	Apr. 30, 2020 USD ($)	Apr. 30, 2019 USD ($)	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)	Jun. 30, 2019 USD ($)
Short-term Debt [Line Items]
Number of days outstanding, prior to springing maturity date			91 days
Value of proved reserves, percentage to mortgage			85.00%
Value of proved developing producing reserves, percentage to mortgage			85.00%
Revolving Credit Facility
Short-term Debt [Line Items]
Debt instrument, face amount		$ 2,100,000,000			$ 160,000,000
Accordion feature, increased commitment		$ 3,000,000,000
Net leverage ratio		3.00
Percentage of aggregate commitments available under credit facility		15.00%
Initial borrowing base	$ 1,900,000,000
Letters of credit aggregate sub-limit		$ 650,000,000
Basket for dividends and distributions, annual limit of available cash	$ 150,000,000
Minimum threshold to activate springing maturity date			$ 500,000,000
Minimum current ratio			1.00
Borrowings outstanding			$ 550,000,000	$ 661,000,000
Letters of credit outstanding			204,839,000	204,726,000
Borrowings and issuance of letters of credit remaining capacity			$ 1,145,161,000	1,234,274,000
Maximum | Revolving Credit Facility
Short-term Debt [Line Items]
Net leverage ratio			4.00
5.875% Senior Notes due 2022
Short-term Debt [Line Items]
Stated rate, debt instrument			5.875%
Midstream | Revolving Credit Facility
Short-term Debt [Line Items]
Letters of credit aggregate sub-limit		600,000,000
Borrowings outstanding			$ 319,000,000	311,750,000
Letters of credit outstanding			30,000
Borrowings and issuance of letters of credit remaining capacity			$ 280,970,000
Increase in available borrowings		$ 250,000,000
Secured leverage ratio			3.00
Total leverage ratio			4.00
Pro forma availability of commitments, percentage			20.00%
Basket for repurchase of LP units tied to Available Cash, annual limit			$ 150,000,000
Basket for repurchase of LP units tied to Available Cash, lifetime limit			200,000,000
Maximum borrowing capacity, letters of credit			$ 100,000,000
Interest coverage ratio			2.50
Revolving credit available for borrowing				$ 288,250,000
Midstream | Minimum | Revolving Credit Facility
Short-term Debt [Line Items]
Total leverage ratio			4.75
Maximum net leverage ratio			5.25
Midstream | Maximum | Revolving Credit Facility
Short-term Debt [Line Items]
Secured leverage ratio			3.50
Total leverage ratio			5.25
Maximum net leverage ratio			5.50
Midstream | 5.875% Senior Notes due 2022 | Minimum
Short-term Debt [Line Items]
Debt instrument, face amount			$ 150,000,000
Midstream | 5.875% Senior Notes due 2022 | Maximum
Short-term Debt [Line Items]
Debt instrument, face amount					$ 150,000,000
Federal Funds Open Rate
Short-term Debt [Line Items]
Basis spread on variable rate			0.50%
Federal Funds Open Rate | Midstream
Short-term Debt [Line Items]
Basis spread on variable rate			0.50%
One-Month LIBOR
Short-term Debt [Line Items]
Basis spread on variable rate			1.00%
One-Month LIBOR | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate			0.75%
One-Month LIBOR | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate			1.75%
One-Month LIBOR | Midstream
Short-term Debt [Line Items]
Basis spread on variable rate			1.00%
One-Month LIBOR | Midstream | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate			0.50%
One-Month LIBOR | Midstream | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate			1.50%
London Interbank Offered Rate (LIBOR) | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate			1.75%
London Interbank Offered Rate (LIBOR) | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate			2.75%
London Interbank Offered Rate (LIBOR) | Midstream | Minimum
Short-term Debt [Line Items]
Basis spread on variable rate			1.50%
London Interbank Offered Rate (LIBOR) | Midstream | Maximum
Short-term Debt [Line Items]
Basis spread on variable rate			2.50%