Derivative Financial Instruments (Natural Gas Liquids Volume And Weighted Average Price) (Details)	3 Months Ended				12 Months Ended
	Dec. 31, 2011 bbl Mmbtu	Sep. 30, 2011 bbl Mmbtu	Jun. 30, 2011 bbl Mmbtu	Mar. 31, 2011 bbl Mmbtu	Dec. 31, 2011 Mmbtu bbl
2011 - Swap Contracts [Member]
Volume	1,150	1,150			1,150
Index price	51.50	51.50			51.50
2011 - Collar Contracts [Member]
Volume	2,650	2,650			2,650
2011 - Collar Contracts [Member] | Ceiling [Member]
Index price	64.23	64.23			64.23
2011 - Collar Contracts [Member] | Floor [Member]
Index price	53.29	53.29			53.29
2012 - Swap Contracts [Member]
Volume	750	750	750	750	750
Index price	35.03	35.03	35.03	35.03	35.03