Derivative Activities (Notional Volumes Of Commodity Derivative Contracts) (Details)	Oct. 31, 2012	Sep. 30, 2012
Oil Positions [Member] | Jul 1 - Dec 31, 2012 [Member] | WTI [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		5,872
Average price		100.34
Oil Positions [Member] | 2013 [Member] | WTI [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	627	6,543
Average price	88.20	99.75
Oil Positions [Member] | 2014 [Member] | WTI [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	1,000	5,661
Average price	87.53	97.91
Oil Positions [Member] | 2014 [Member] | WTI [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] | WTI [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	931	4,540
Average price	85.65	96.87
Oil Positions [Member] | 2015 [Member] | WTI [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] | WTI [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	868	2,480
Average price	84.65	92.07
Oil Positions [Member] | 2016 [Member] | WTI [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] | WTI [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	817	3,730
Average price	84.35	87.57
Natural Gas Positions [Member] | Jul 1 - Dec 31, 2012 [Member] | NYMEX [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		30,213
Average price		5.89
Natural Gas Positions [Member] | Jul 1 - Dec 31, 2012 [Member] | NYMEX [Member] | Basis Swaps [Member]
Derivative [Line Items]
Hedged volume per day		20,709
Average price		(0.15)
Natural Gas Positions [Member] | Jul 1 - Dec 31, 2012 [Member] | Henry Hub [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day		2,609
Average floor price		6.50
Average ceiling price		8.60
Natural Gas Positions [Member] | 2013 [Member] | NYMEX [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		29,674
Average price		6.07
Natural Gas Positions [Member] | 2013 [Member] | NYMEX [Member] | Basis Swaps [Member]
Derivative [Line Items]
Hedged volume per day		18,466
Average price		(0.17)
Natural Gas Positions [Member] | 2013 [Member] | Henry Hub [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	767
Average price	3.99
Natural Gas Positions [Member] | 2013 [Member] | Henry Hub [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day		2,466
Average floor price		6.50
Average ceiling price		8.65
Natural Gas Positions [Member] | 2014 [Member] | NYMEX [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		25,907
Average price		6.23
Natural Gas Positions [Member] | 2014 [Member] | NYMEX [Member] | Basis Swaps [Member]
Derivative [Line Items]
Hedged volume per day		17,066
Average price		(0.19)
Natural Gas Positions [Member] | 2014 [Member] | Henry Hub [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	715
Average price	4.27
Natural Gas Positions [Member] | 2014 [Member] | Henry Hub [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day		4,966
Average floor price		5.74
Average ceiling price		7.51
Natural Gas Positions [Member] | 2015 [Member] | NYMEX [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		6,520
Average price		5.43
Natural Gas Positions [Member] | 2015 [Member] | NYMEX [Member] | Basis Swaps [Member]
Derivative [Line Items]
Hedged volume per day		14,400
Average price		(0.19)
Natural Gas Positions [Member] | 2015 [Member] | Henry Hub [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day	671
Average price	4.43
Natural Gas Positions [Member] | 2015 [Member] | Henry Hub [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day		18,000
Average floor price		5.00
Average ceiling price		7.48
Natural Gas Positions [Member] | 2015 [Member] | Henry Hub [Member] | Put [Member]
Derivative [Line Items]
Hedged volume per day		420
Average price		4.0
Natural Gas Positions [Member] | 2016 [Member] | NYMEX [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		11,350
Average price		4.27
Natural Gas Positions [Member] | 2016 [Member] | Henry Hub [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	630
Average floor price	4.00
Average ceiling price	5.55
Natural Gas Positions [Member] | 2016 [Member] | Henry Hub [Member] | Put [Member]
Derivative [Line Items]
Hedged volume per day		11,350
Average price		4.0
Natural Gas Positions [Member] | 2017 [Member] | NYMEX [Member] | Swaps [Member]
Derivative [Line Items]
Hedged volume per day		10,445
Average price		4.47
Natural Gas Positions [Member] | 2017 [Member] | Henry Hub [Member] | Collars [Member]
Derivative [Line Items]
Hedged volume per day	595
Average floor price	4.00
Average ceiling price	6.15
Natural Gas Positions [Member] | 2017 [Member] | Henry Hub [Member] | Put [Member]
Derivative [Line Items]
Hedged volume per day		10,445
Average price		4.0