Derivative Instruments and Hedging Activities (Details 2)	Aug. 02, 2012
2012 Hedging Position One [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	5.035
2012 Hedging Position One [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	90.30
2012 Hedging Position Two [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	5.040
2012 Hedging Position Two [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	90.41
2012 Hedging Position Three [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	5.050
2012 Hedging Position Three [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	90.45
2012 Hedging Position Four [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	95.50
2012 Hedging Position Five [Member] | Oil [Member]
Hedging Positions
Daily Volume	2,000
Swap Price	97.60
2012 Hedging Position Six [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	98.15
2012 Hedging Position Seven [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	100.00
2012 Hedging Position Eight [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	101.55
2012 Hedging Position Nine [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	104.25
2012 Hedging Position Ten [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	111.02
2013 Hedging Position One [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	5.270
2013 Hedging Position One [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	92.80
2013 Hedging Position Two [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	5.320
2013 Hedging Position Two [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	94.45
2013 Hedging Position Three [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	94.60
2013 Hedging Position Four [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	97.15
2013 Hedging Position Five [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	101.53
2013 Hedging Position Six [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	103.00
2013 Hedging Position Seven [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	103.15
2013 Hedging Position Eight [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	104.25
2013 Hedging Position Nine [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	104.47
2013 Hedging Position Ten [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	104.50
2013 Hedging Position Eleven [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	107.30
2014 Hedging Position One [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	4.000
2014 Hedging Position One [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	90.06
2014 Hedging Position Two [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	98.00
2014 Hedging Position Three [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	98.30
2014 Hedging Position Four [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	99.65
2014 Hedging Position Five [Member] | Oil [Member]
Hedging Positions
Daily Volume	1,000
Swap Price	103.30
2015 Hedging Position One [Member] | Natural Gas [Member]
Hedging Positions
Daily Volume	10,000
Swap Price	4.005