Derivative Financial Instruments (Schedule Of Open Oil Derivative Positions) (Details)	3 Months Ended
	Mar. 31, 2021 $ / bbl bbl
NYMEX West Texas Intermediate Price Swaps Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	81,122
Weighted Average Price Swap	40.45
NYMEX West Texas Intermediate Price Collars Oil Q1-Q4 2022 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	25,619
Weighted Average Price Swap	43.82
NYMEX West Texas Intermediate Price Swaptions Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	6,691
Weighted Average Price Swap	40.12
NYMEX West Texas Intermediate Price Swaptions Oil Q1-Q4 2022 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	10,323
Weighted Average Price Swap	46.46
NYMEX West Texas Intermediate Price Collars Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	40,905
Weighted Average Floor Price	39.84
Weighted Average Ceiling Price	49.84
NYMEX West Texas Intermediate Price Collars Oil Q1-Q4 2022 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	15,733
Weighted Average Floor Price	44.92
Weighted Average Ceiling Price	54.92
NYMEX West Texas Intermediate Call Options Sold Oil Q1-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	5,000
Weighted Average Price Swap	39.50
Midland Sweet Basis Swaps Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	22,669
Oil Basis Swaps	0.84
Guernsey Light Sweet Basis Swaps Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	2,007
Oil Basis Swaps	(1.48)
BRENT Basis Swaps Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	1,000
Oil Basis Swaps	(8.00)
NYMEX Roll Basis Swaps Oil Q2-Q4 2021 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	11,676
Oil Basis Swaps	0.38
BRENT Basis Swaps Oil Q1-Q4 2022 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	1,000
Oil Basis Swaps	(7.75)
NYMEX Roll Basis Swaps Oil Q1-Q4 2022 [Member]
Derivative [Line Items]
Volume Per Day (Bbls/d) | bbl	16,000
Oil Basis Swaps	0.37