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, 2019 MMBTU $ / bbl $ / MMBTU bbl	Dec. 31, 2021 MMBTU $ / bbl $ / MMBTU bbl	Dec. 31, 2020 MMBTU $ / bbl $ / MMBTU bbl
Commodity - Oil | Put spreads
Derivative [Line Items]
Total volume (Bbls) | bbl	460,000	0	0
Commodity - Oil | Collar contracts with short puts (three-way collars)
Derivative [Line Items]
Total volume (Bbls) | bbl	2,392,000	0	3,294,000
Commodity - Oil | Oil contracts (Midland basis differential)
Derivative [Line Items]
Total volume (Bbls) | bbl	4,137,500	1,095,000	4,576,000
Weighted average swap price (in dollars per share)	(2.64)	(1.00)	(1.29)
Commodity - Oil | Oil contracts (Argus Houston MEH basis differential)
Derivative [Line Items]
Total volume (Bbls) | bbl	0	0	552,000
Strike price (in dollars per share) | $ / MMBTU	0	0	3.30
Commodity - Oil | Put option
Derivative [Line Items]
Total volume (Bbls) | bbl	460,000	0	0
Strike price (in dollars per share)	65.00	0	0
Commodity - Oil | Put option | Put spreads | Long
Derivative [Line Items]
Strike price (in dollars per share)	65.00	0	0
Commodity - Oil | Put option | Put spreads | Short
Derivative [Line Items]
Strike price (in dollars per share)	42.50	0	0
Commodity - Oil | Put option | Collar contracts with short puts (three-way collars) | Long
Derivative [Line Items]
Strike price (in dollars per share)	56.54	0	55.69
Commodity - Oil | Put option | Collar contracts with short puts (three-way collars) | Short
Derivative [Line Items]
Strike price (in dollars per share)	43.65	0	44.47
Commodity - Oil | Call option | Collar contracts with short puts (three-way collars) | Short
Derivative [Line Items]
Strike price (in dollars per share)	67.46	0	65.72
Commodity - Natural gas | Swap contracts
Derivative [Line Items]
Strike price (in dollars per share) | $ / MMBTU	2.89	0	0
Total volume (MMBtu) | MMBTU	1,397,000	0	0
Commodity - Natural gas | Collar contracts (two-way collars)
Derivative [Line Items]
Total volume (MMBtu) | MMBTU	1,196,000	0	0
Commodity - Natural gas | Collar contracts (two-way collars) | Long
Derivative [Line Items]
Strike price (in dollars per share) | $ / MMBTU	3.13	0	0
Commodity - Natural gas | Collar contracts (two-way collars) | Short
Derivative [Line Items]
Strike price (in dollars per share) | $ / MMBTU	3.50	0	0
Commodity - Natural gas | Waha basis differential | Swap contracts
Derivative [Line Items]
Total volume (MMBtu) | MMBTU	4,232,000	0	4,758,000
Weighted average swap price (in dollars per share) | $ / MMBTU	(1.18)	0	(1.12)