Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified			9 Months Ended					9 Months Ended														9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas contract 1 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas contract 2 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas contract 3 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas Contract 4 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 1 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 2 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 3 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 4 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 5 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 6 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 7 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 8 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 9 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 10 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 11 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 12 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Oil [Member] Oil contract 13 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas [Member] Natural Gas contract 1 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas [Member] Natural Gas contract 2 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas [Member] Natural Gas contract 3 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas [Member] Natural Gas Contract 4 [Member]	Sep. 30, 2012 Open costless collar contracts [Member] Natural Gas [Member] Natural Gas Contract 5 [Member]
Summary of contracts for oil and natural gas
Calculation Period			01/01/2013 - 12/31/2013	01/01/2013 - 12/31/2013	01/01/2014 - 12/31/2014	01/01/2014 - 12/31/2014		10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 03/31/2013	01/01/2013 – 12/31/2013	01/01/2013 – 12/31/2013	01/01/2013 – 12/31/2013	01/01/2013 – 12/31/2013	01/01/2013 – 06/30/2014	01/01/2013 – 06/30/2014		10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 12/31/2012	10/01/2012 – 07/31/2013	10/01/2012 – 12/31/2013
Notional Quantity			100,000	100,000	100,000	100,000		20,000	10,000	10,000	20,000	20,000	20,000	20,000	20,000	20,000	20,000	20,000	8,000	12,000		300,000	150,000	70,000	150,000	100,000
Price Floor			3.00	3.00	3.25	3.25		90.00	90.00	90.00	90.00	90.00	95.00	90.00	85.00	90.00	85.00	85.00	90.00	90.00		4.50	4.25	2.50	4.50	3.00
Price Ceiling			4.95	4.96	5.37	5.42		104.20	108.00	109.50	111.00	111.90	116.00	110.00	102.25	115.00	110.40	108.80	114.00	115.50		5.60	6.17	3.34	5.75	3.83
Fair Value of Asset (Liability)	$ 8,133	$ 9,282					$ 5,616	$ 113	$ 65	$ 68	$ 139	$ 141	$ 291	$ 356	$ 61	$ 1,233	$ 598	$ 515	$ 794	$ 1,242	$ 2,472	$ 1,067	$ 424	$ (36)	$ 1,398	$ (381)