Derivatives (Summary Of Derivative Instruments Contracts) (Details)	Dec. 31, 2020 MMBTU $ / MMBTU $ / bbl bbl
Natural Gas Costless Collars [Member] | Derivative Contract Period One [Member]
Derivative [Line Items]
Contract total volume - Gas/Natural gas | MMBTU	2,924,500
Natural Gas Costless Collars [Member] | Derivative Contract Period One [Member] | Minimum [Member]
Derivative [Line Items]
Contract average price | $ / MMBTU	2.33
Natural Gas Costless Collars [Member] | Derivative Contract Period One [Member] | Maximum [Member]
Derivative [Line Items]
Contract average price | $ / MMBTU	3.03
Natural Gas Costless Collars [Member] | Derivative Contract Period Two [Member]
Derivative [Line Items]
Contract total volume - Gas/Natural gas | MMBTU	1,402,500
Natural Gas Costless Collars [Member] | Derivative Contract Period Two [Member] | Minimum [Member]
Derivative [Line Items]
Contract average price | $ / MMBTU	2.47
Natural Gas Costless Collars [Member] | Derivative Contract Period Two [Member] | Maximum [Member]
Derivative [Line Items]
Contract average price | $ / MMBTU	3.14
Natural Gas Fixed Price Swaps [Member] | Derivative Contract Period Three [Member]
Derivative [Line Items]
Contract total volume - Gas/Natural gas | MMBTU	1,014,500
Contract average price | $ / MMBTU	2.69
Natural Gas Fixed Price Swaps [Member] | Derivative Contract Period Four [Member]
Derivative [Line Items]
Contract total volume - Gas/Natural gas | MMBTU	125,500
Contract average price | $ / MMBTU	2.70
Oil Costless Collars [Member] | Derivative Contract Period Five [Member]
Derivative [Line Items]
Contract total volume - Oil | bbl	51,000
Oil Costless Collars [Member] | Derivative Contract Period Five [Member] | Minimum [Member]
Derivative [Line Items]
Contract average price | $ / bbl	36.74
Oil Costless Collars [Member] | Derivative Contract Period Five [Member] | Maximum [Member]
Derivative [Line Items]
Contract average price | $ / bbl	44.79
Oil Costless Collars [Member] | Derivative Contract Period Six [Member]
Derivative [Line Items]
Contract total volume - Oil | bbl	23,500
Oil Costless Collars [Member] | Derivative Contract Period Six [Member] | Minimum [Member]
Derivative [Line Items]
Contract average price | $ / bbl	36.89
Oil Costless Collars [Member] | Derivative Contract Period Six [Member] | Maximum [Member]
Derivative [Line Items]
Contract average price | $ / bbl	45.73
Oil Fixed Price Swaps [Member] | Derivative Contract Period Seven [Member]
Derivative [Line Items]
Contract average price | $ / bbl	37.00
Contract total volume - Oil | bbl	96,000
Oil Fixed Price Swaps [Member] | Derivative Contract Period Eight [Member]
Derivative [Line Items]
Contract average price | $ / bbl	41.51
Contract total volume - Oil | bbl	59,000