Derivative Activities (Notional Volumes Of Commodity Derivative Contracts) (Details)	3 Months Ended
	Mar. 31, 2013
Oil Positions [Member] | Swaps [Member]
Derivative [Line Items]
Index	WTI
Oil Positions [Member] | Swap 2 [Member]
Derivative [Line Items]
Index	LLS
Oil Positions [Member] | Basis Swap [Member]
Derivative [Line Items]
Index	WTS/WTI
Oil Positions [Member] | Collars [Member]
Derivative [Line Items]
Index	WTI
Oil Positions [Member] | April 1 - Dec 31, 2013 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	7,635
Average price	98.61
Oil Positions [Member] | April 1 - Dec 31, 2013 [Member] | Swap 2 [Member]
Derivative [Line Items]
Hedged volume per day	1,400
Average price	99.51
Oil Positions [Member] | April 1 - Dec 31, 2013 [Member] | Basis Swap [Member]
Derivative [Line Items]
Hedged volume per day	2,400
Average price	(1.90)
Oil Positions [Member] | 2014 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	7,125
Average price	96.17
Oil Positions [Member] | 2014 [Member] | Swap 2 [Member]
Derivative [Line Items]
Hedged volume per day	1,900
Average price	98.77
Oil Positions [Member] | 2014 [Member] | Basis Swap [Member]
Derivative [Line Items]
Hedged volume per day	2,400
Average price	(2.10)
Oil Positions [Member] | 2014 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	425
Average floor price	90.00
Average ceiling price	106.50
Oil Positions [Member] | 2015 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	6,721
Average price	94.52
Oil Positions [Member] | 2015 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	1,025
Average floor price	90.00
Average ceiling price	110.00
Oil Positions [Member] | 2016 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	5,698
Average price	90.81
Oil Positions [Member] | 2016 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	1,500
Average floor price	80.00
Average ceiling price	102.00
Oil Positions [Member] | 2017 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	4,997
Average price	86.88
Natural Gas Position [Member] | Swaps [Member]
Derivative [Line Items]
Index	Henry Hub
Natural Gas Position [Member] | Basis Swap [Member]
Derivative [Line Items]
Index	Henry Hub
Natural Gas Position [Member] | Collars [Member]
Derivative [Line Items]
Index	Henry Hub
Natural Gas Position [Member] | Put [Member]
Derivative [Line Items]
Index	Henry Hub
Natural Gas Position [Member] | April 1 - Dec 31, 2013 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	30,419
Average price	5.97
Natural Gas Position [Member] | April 1 - Dec 31, 2013 [Member] | Basis Swap [Member]
Derivative [Line Items]
Hedged volume per day	18,455
Average price	(0.17)
Natural Gas Position [Member] | April 1 - Dec 31, 2013 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	2,455
Average floor price	6.50
Average ceiling price	8.65
Natural Gas Position [Member] | 2014 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	26,622
Average price	6.18
Natural Gas Position [Member] | 2014 [Member] | Basis Swap [Member]
Derivative [Line Items]
Hedged volume per day	17,066
Average price	(0.19)
Natural Gas Position [Member] | 2014 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	4,966
Average floor price	5.74
Average ceiling price	7.51
Natural Gas Position [Member] | 2015 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	7,191
Average price	5.34
Natural Gas Position [Member] | 2015 [Member] | Basis Swap [Member]
Derivative [Line Items]
Hedged volume per day	14,400
Average price	(0.19)
Natural Gas Position [Member] | 2015 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	18,000
Average floor price	5.00
Average ceiling price	7.48
Natural Gas Position [Member] | 2015 [Member] | Put [Member]
Derivative [Line Items]
Hedged volume per day	420
Average price	4.00
Natural Gas Position [Member] | 2016 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	11,350
Average price	4.27
Natural Gas Position [Member] | 2016 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	630
Average floor price	4.00
Average ceiling price	5.55
Natural Gas Position [Member] | 2016 [Member] | Put [Member]
Derivative [Line Items]
Hedged volume per day	11,350
Average price	4.00
Natural Gas Position [Member] | 2017 [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	10,445
Average price	4.47
Natural Gas Position [Member] | 2017 [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	595
Average floor price	4.00
Average ceiling price	6.15
Natural Gas Position [Member] | 2017 [Member] | Put [Member]
Derivative [Line Items]
Hedged volume per day	10,445
Average price	4.00