Derivatives (Non-Qualifying Cash Flow Derivatives Outstanding) (Details) (USD $)	6 Months Ended
	Jun. 30, 2011
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] | 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] | 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] | 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] | 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] | 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] | 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]
Hedged Volume (MMBtu/day)	10,000
Basis Differential	$ (0.23)
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
Basis Differential	(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]
Hedged Volume (MMBtu/day)	10,000
Basis Differential	$ (0.21)
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