Derivatives (Cash Flow Hedges Outstanding) (Details)	6 Months Ended
	Jun. 30, 2011 bbl
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jan'12 - Dec'12 [Member]
Hedged Volume (in Bbl/day)	4,500
Weighted Average Fixed Price for Swaps	95.91
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jan'12 - Dec'12 [Member] | Start [Member]
Commodity Derivatives Term	Jan'12
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jan'12 - Dec'12 [Member] | End [Member]
Commodity Derivatives Term	Dec'12
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jul'11 - Dec'11 [Member]
Hedged Volume (in Bbl/day)	4,000
Weighted Average Fixed Price for Swaps	84.28
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jan'13 - Dec'13 [Member]
Hedged Volume (in Bbl/day)	2,000
Weighted Average Fixed Price for Swaps	102.05
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jan'13 - Dec'13 [Member] | Start [Member]
Commodity Derivatives Term	Jan'13
Swap [Member] | WTI - NYMEX [Member] | Crude Oil [Member] | Jan'13 - Dec'13 [Member] | End [Member]
Commodity Derivatives Term	Dec'13
Swap [Member] | IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member]
Hedged Volume (MMBtu/day)	30,000
Weighted Average Fixed Price for Swaps	5.05
Swap [Member] | IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | Start [Member]
Commodity Derivatives Term	Jan'12
Swap [Member] | IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | End [Member]
Commodity Derivatives Term	Dec'12
Swap [Member] | IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member]
Hedged Volume (MMBtu/day)	70,000
Weighted Average Fixed Price for Swaps	4.87
Swap [Member] | IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Swap [Member] | IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11
Swap [Member] | IF - PEPL [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member]
Hedged Volume (MMBtu/day)	15,000
Weighted Average Fixed Price for Swaps	5.62
Swap [Member] | IF - PEPL [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | Start [Member]
Commodity Derivatives Term	Jan'12
Swap [Member] | IF - PEPL [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | End [Member]
Commodity Derivatives Term	Dec'12
Swap [Member] | OPIS - Conway [Member] | Liquids [Member] | Jul'11 - Dec'11 [Member]
Hedged Volume (Gal/mo)	644,406	[1]
Weighted Average Fixed Price for Swaps	0.97	[1]
Swap [Member] | OPIS - Conway [Member] | Liquids [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Swap [Member] | OPIS - Conway [Member] | Liquids [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11
Swap [Member] | CEGT - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member]
Hedged Volume (MMBtu/day)	10,000
Weighted Average Fixed Price for Swaps	4.43
Swap [Member] | CEGT - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Swap [Member] | CEGT - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11
Basis Swap [Member] | PEPL - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Basis Swap [Member] | PEPL - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11
Basis Swap [Member] | Tenn Zone - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member]
Hedged Volume (MMBtu/day)	15,000
Weighted Average Fixed Price for Swaps	(0.14)
Basis Swap [Member] | Tenn Zone - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Basis Swap [Member] | Tenn Zone - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11
Basis Swap [Member] | CEGT - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | Start [Member]
Commodity Derivatives Term	Jul'11
Basis Swap [Member] | CEGT - NYMEX [Member] | Natural Gas [Member] | Jul'11 - Dec'11 [Member] | End [Member]
Commodity Derivatives Term	Dec'11

[1] Types of liquids involved are natural gasoline, ethane, propane, isobutane and normal butane.