Derivative Instruments and Hedging Activities (Schedule of Derivative Instruments Outstanding) (Details)	Jun. 30, 2013
July 2013 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	11,445
Volume	354,800
Average Swap Price	104.87
July 2013 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	9,000
Volume	279,000
Average Swap Price	3.53
August 2013 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,219
Volume	192,800
Average Swap Price	104.70
August 2013 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	8,500
Volume	263,500
Average Swap Price	3.55
September 2013 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,233
Volume	187,000
Average Swap Price	104.45
September 2013 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	8,500
Volume	255,000
Average Swap Price	3.55
October 2013 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	5,719
Volume	177,300
Average Swap Price	103.94
October 2013 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	8,000
Volume	248,000
Average Swap Price	3.58
November 2013 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,233
Volume	187,000
Average Swap Price	103.93
November 2013 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	7,500
Volume	225,000
Average Swap Price	3.67
December 2013 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	9,156
Volume	283,850
Average Swap Price	103.24
December 2013 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,500
Volume	201,500
Average Swap Price	3.83
2013 Totals [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	7,515
Volume	1,382,750
Average Swap Price	104.21
2013 Totals [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	8,000
Volume	1,472,000
Average Swap Price	3.61
January 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	11,250
Volume	348,750
Average Swap Price	101.08
February 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	11,250
Volume	315,000
Average Swap Price	101.08
March 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	11,250
Volume	348,750
Average Swap Price	101.08
April 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	10,250
Volume	307,500
Average Swap Price	101.26
May 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	10,250
Volume	317,750
Average Swap Price	101.26
June 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	10,250
Volume	307,500
Average Swap Price	101.26
July 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	10,250
Volume	317,750
Average Swap Price	101.26
August 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,000
Volume	186,000
Average Swap Price	101.00
September 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,000
Volume	180,000
Average Swap Price	101.00
October 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,000
Volume	186,000
Average Swap Price	101.00
November 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,000
Volume	180,000
Average Swap Price	101.00
December 2014 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	6,000
Volume	186,000
Average Swap Price	101.00
2014 Totals [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	8,715
Volume	3,181,000
Average Swap Price	101.13
July 2013 To December 2013 [Member] | Oil Contract [Member] | Collars [Member]
Derivative [Line Items]
Daily Average Volume	1,000
Volume	184,000
July 2013 To December 2013 [Member] | Oil Contract [Member] | Collars [Member] | Minimum [Member]
Derivative [Line Items]
Average Swap Price	80.00
July 2013 To December 2013 [Member] | Oil Contract [Member] | Collars [Member] | Maximum [Member]
Derivative [Line Items]
Average Swap Price	104.10
January 2014 To December 2014 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	5,000
Volume	1,825,000
Average Swap Price	4.01
January 2015 To December 2015 [Member] | Oil Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	1,500
Volume	547,500
Average Swap Price	97.70
January 2015 To December 2015 [Member] | Gas Contract [Member] | Fixed Price Swaps [Member]
Derivative [Line Items]
Daily Average Volume	4,300
Volume	1,569,500
Average Swap Price	4.31