Derivative Financial Instruments (Oil Derivative Contracts Volume And Weighted Average Price) (Details)	12 Months Ended
	Dec. 31, 2019 bbl / d $ / bbl $ / MMBTU
Brent swap contracts, First Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	3,407
Brent swap contracts, First Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	60.86
Brent swap contracts, Second Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent swap contracts, Second Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent swap contracts, Third Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent swap contracts, Third Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent swap contracts, Fourth Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent swap contracts, Fourth Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent swap contracts, Next Year | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent swap contracts, Next Year | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent collar contracts with short puts, First Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	145,500
Brent collar contracts with short puts, First Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Ceiling, price per barrel | $ / bbl	68.46
Floor, price per barrel | $ / bbl	61.64
Short put, price per barrel | $ / bbl	53.45
Brent collar contracts with short puts, Second Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	135,500
Brent collar contracts with short puts, Second Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Ceiling, price per barrel | $ / bbl	68.84
Floor, price per barrel | $ / bbl	61.76
Short put, price per barrel | $ / bbl	53.48
Brent collar contracts with short puts, Third Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	115,500
Brent collar contracts with short puts, Third Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Ceiling, price per barrel | $ / bbl	69.78
Floor, price per barrel | $ / bbl	62.06
Short put, price per barrel | $ / bbl	53.56
Brent collar contracts with short puts, Fourth Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	115,500
Brent collar contracts with short puts, Fourth Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Ceiling, price per barrel | $ / bbl	69.78
Floor, price per barrel | $ / bbl	62.06
Short put, price per barrel | $ / bbl	53.56
Brent collar contracts with short puts, Next Year | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	7,000
Brent collar contracts with short puts, Next Year | Oil contracts, price per bbl
Derivative [Line Items]
Ceiling, price per barrel | $ / bbl	65.37
Floor, price per barrel | $ / bbl	60.00
Short put, price per barrel | $ / bbl	52.00
Brent call contracts sold, First Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent call contracts sold, First Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent call contracts sold, Second Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent call contracts sold, Second Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent call contracts sold, Third Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent call contracts sold, Third Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent call contracts sold, Fourth Quarter | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	0
Brent call contracts sold, Fourth Quarter | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	0
Brent call contracts sold, Next Year | Oil contracts
Derivative [Line Items]
Volume per day (Bbl) | bbl / d	13,000
Brent call contracts sold, Next Year | Oil contracts, price per bbl
Derivative [Line Items]
Price per MMBtu in usd | $ / MMBTU	72.10