Quarterly report pursuant to Section 13 or 15(d)

Derivative Instruments and Hedging Activities (Schedule of Outstanding Oil and Natural Gas Derivative Contracts) (Details)

v3.10.0.1
Derivative Instruments and Hedging Activities (Schedule of Outstanding Oil and Natural Gas Derivative Contracts) (Details) - Forecast - Not Designated as Hedging Instrument
 6 Months Ended 12 Months Ended
Dec. 31, 2018
MMBTU
$ / MMBTU
bbl
Dec. 31, 2020
MMBTU
$ / MMBTU
bbl
Dec. 31, 2019
MMBTU
$ / MMBTU
bbl
Oil | Put option      
Derivative [Line Items]      
Total volume (Bbls) | bbl 552,000,000 0 1,825,000,000
Average swap price (in dollars per share) 65.00 0.00 65.00
Oil | Swap contracts      
Derivative [Line Items]      
Total volume (Bbls) | bbl 1,104,000,000 0 0
Average swap price (in dollars per share) 52.07 0.00 0.00
Oil | Collar contracts (two-way collars)      
Derivative [Line Items]      
Total volume (Bbls) | bbl 184,000,000 0 0
Oil | Collar contracts (two-way collars) | Short      
Derivative [Line Items]      
Strike price (in dollars per share) 60.50 0 0
Oil | Collar contracts (two-way collars) | Long      
Derivative [Line Items]      
Strike price (in dollars per share) 50 0 0
Oil | Collar contracts combined with short puts (three-way collars)      
Derivative [Line Items]      
Total volume (Bbls) | bbl 1,748,000,000 0 3,469,000,000
Oil | Collar contracts combined with short puts (three-way collars) | Call option | Short      
Derivative [Line Items]      
Strike price (in dollars per share) 60.86 0 63.71
Oil | Collar contracts combined with short puts (three-way collars) | Put option | Short      
Derivative [Line Items]      
Strike price (in dollars per share) 39.21 0 43.95
Oil | Collar contracts combined with short puts (three-way collars) | Put option | Long      
Derivative [Line Items]      
Strike price (in dollars per share) 48.95 0 53.95
Oil | Oil contracts (Midland basis differential)      
Derivative [Line Items]      
Total volume (Bbls) | bbl 2,208,000,000 3,660,000,000 4,380,000,000
Oil | Oil contracts (Midland basis differential) | Short      
Derivative [Line Items]      
Average swap price (in dollars per share) 4.26 1.47 4.77
Natural gas | Swap contracts      
Derivative [Line Items]      
Average swap price (in dollars per share) 2.91 0 0
Total volume (MMBtu) | MMBTU 2,760,000,000 0 0
Natural gas | Collar contracts (two-way collars)      
Derivative [Line Items]      
Total volume (MMBtu) | MMBTU 1,104,000,000 0 2,372,500,000
Natural gas | Collar contracts (two-way collars) | Short      
Derivative [Line Items]      
Strike price (in dollars per share) 3.19 0 2.95
Natural gas | Collar contracts (two-way collars) | Long      
Derivative [Line Items]      
Strike price (in dollars per share) 2.75 0 2.65
Natural gas | Waha basis differential | Swap contracts      
Derivative [Line Items]      
Total volume (MMBtu) | MMBTU 1,104,000,000 2,196,000,000 2,190,000,000
Natural gas | Waha basis differential | Swap contracts | Short      
Derivative [Line Items]      
Average swap price (in dollars per share) 1.14 1.14 1.14