Derivative Financial Instruments (Schedule Of Oil Derivative Contracts Volume And Weighted Average Prices) (Details)	3 Months Ended
	Mar. 31, 2013
Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
NYMEX swap multiple, second nearby month	0.6667
NYMEX swap multiple, third nearby month	0.3333
Oil contracts [Member] | Two Thousand Thirteen Collar Contracts With Short Puts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	72,430
Oil contracts [Member] | Two Thousand Fourteen Collar Contracts With Short Puts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	69,000
Oil contracts [Member] | Two Thousand Fifteen Collar Contracts With Short Puts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	26,000
Oil contracts [Member] | Two Thousand Thirteen Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	3,000
Oil contracts [Member] | Two Thousand Fourteen Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts [Member] | 2015 Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts [Member] | 2013 Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	6,000
Oil contracts [Member] | Two Thousand Fourteen Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	15,000
Oil contracts [Member] | Two Thousand Fifteen Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts [Member] | 2013 Mid Cush Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	1,655
Oil contracts [Member] | 2014 Mid Cush Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts [Member] | 2015 Mid Cush Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts [Member] | 2013 Cushing LLS Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	669
Oil contracts [Member] | 2014 Cushing LLS Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts [Member] | 2015 Cushing LLS Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Average daily oil production derivative barrels per day	0
Oil contracts, price per bbl [Member] | Two Thousand Thirteen Collar Contracts With Short Puts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Average Cap Price	119.89
Derivative, Average Floor Price	92.26
Oil contracts, price per bbl [Member] | Two Thousand Thirteen Collar Contracts With Short Puts [Member] | Short Put [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	74.36
Oil contracts, price per bbl [Member] | Two Thousand Fourteen Collar Contracts With Short Puts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Average Cap Price	114.05
Derivative, Average Floor Price	93.70
Oil contracts, price per bbl [Member] | Two Thousand Fourteen Collar Contracts With Short Puts [Member] | Short Put [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	77.61
Oil contracts, price per bbl [Member] | Two Thousand Fifteen Collar Contracts With Short Puts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Average Cap Price	104.45
Derivative, Average Floor Price	95.00
Oil contracts, price per bbl [Member] | Two Thousand Fifteen Collar Contracts With Short Puts [Member] | Short Put [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	80.00
Oil contracts, price per bbl [Member] | Two Thousand Thirteen Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Swap Type, Average Fixed Price	81.02
Oil contracts, price per bbl [Member] | Two Thousand Fourteen Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Swap Type, Average Fixed Price	0.00
Oil contracts, price per bbl [Member] | 2015 Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Swap Type, Average Fixed Price	0.00
Oil contracts, price per bbl [Member] | 2013 Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.43	[1]
Oil contracts, price per bbl [Member] | Two Thousand Fourteen Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.38	[1]
Oil contracts, price per bbl [Member] | Two Thousand Fifteen Rollfactor Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.00	[1]
Oil contracts, price per bbl [Member] | 2013 Mid Cush Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	(5.75)	[2]
Oil contracts, price per bbl [Member] | 2014 Mid Cush Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.00	[2]
Oil contracts, price per bbl [Member] | 2015 Mid Cush Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.00	[2]
Oil contracts, price per bbl [Member] | 2013 Cushing LLS Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	(9.30)	[3]
Oil contracts, price per bbl [Member] | 2014 Cushing LLS Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.00	[3]
Oil contracts, price per bbl [Member] | 2015 Cushing LLS Basis Swap Contracts [Member]
Trading Activity, Gains and Losses, Net [Line Items]
Derivative, Nonmonetary Notional Amount, Price Per Unit	0.00	[3]

[1] Represents swaps that fix the difference between (i) each day's price per BBL of WTI for the first nearby month less (ii) the price per BBL of WTI for the second nearby NYMEX month, multiplied by .6667; plus (iii) each day's price per BBL of WTI for the first nearby month less (iv) the price per BBL of WTI for the third nearby NYMEX month, multiplied by .3333.

[2] Basis differential price between Midland WTI and Cushing WTI.

[3] Basis differential price between Cushing WTI and Louisiana Light Sweet crude "LLS".