Derivative Financial Instruments (Schedule Of Gas Volume And Weighted Average Prices) (Details)	3 Months Ended
	Mar. 31, 2012
2012 - Swap Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	275,000
Price per MMBtu	4.97
2012 - Collar Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	65,000
2012 - Collar Contracts [Member] | Ceiling [Member]
Derivative [Line Items]
Price per MMBtu	6.60
2012 - Collar Contracts [Member] | Floor [Member]
Derivative [Line Items]
Price per MMBtu	5.00
2012 - Basis Swap Contracts [Member] 2012 - Basic Swap Contracts
Derivative [Line Items]
Volume (MMBtu)	136,000
Price per MMBtu	(0.34)
2013 - Swap Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	112,500
Price per MMBtu	5.62
2013 - Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	150,000
2013 - Contracts [Member] | Ceiling [Member]
Derivative [Line Items]
Price per MMBtu	6.25
2013 - Contracts [Member] | Floor [Member]
Derivative [Line Items]
Price per MMBtu	5.00
2013 - Basis Swap Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	142,500
Price per MMBtu	(0.22)
2014 - Swap Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	50,000
Price per MMBtu	6.05
2014 - Collar Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	140,000
2014 - Collar Contracts [Member] | Ceiling [Member]
Derivative [Line Items]
Price per MMBtu	6.44
2014 - Collar Contracts [Member] | Floor [Member]
Derivative [Line Items]
Price per MMBtu	5.00
2014 - Collar Contracts With Short Puts [Member]
Derivative [Line Items]
Volume (MMBtu)	60,000
2014 - Collar Contracts With Short Puts [Member] | Ceiling [Member]
Derivative [Line Items]
Price per MMBtu	7.80
2014 - Collar Contracts With Short Puts [Member] | Floor [Member]
Derivative [Line Items]
Price per MMBtu	5.83
2014 - Collar Contracts With Short Puts [Member] | Short Put [Member]
Derivative [Line Items]
Price per MMBtu	4.42
2014 - Basic Swap Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	115,000
Price per MMBtu	(0.23)
2015 - Collar Contracts [Member]
Derivative [Line Items]
Volume (MMBtu)	50,000
2015 - Collar Contracts [Member] | Ceiling [Member]
Derivative [Line Items]
Price per MMBtu	7.92
2015 - Collar Contracts [Member] | Floor [Member]
Derivative [Line Items]
Price per MMBtu	5.00
2015 - Collar Contracts With Short Puts [Member]
Derivative [Line Items]
Volume (MMBtu)	30,000
2015 - Collar Contracts With Short Puts [Member] | Ceiling [Member]
Derivative [Line Items]
Price per MMBtu	7.11
2015 - Collar Contracts With Short Puts [Member] | Floor [Member]
Derivative [Line Items]
Price per MMBtu	5.00
2015 - Collar Contracts With Short Puts [Member] | Short Put [Member]
Derivative [Line Items]
Price per MMBtu	4.00