Derivatives (Cash Flow Hedges Outstanding) (Details) (Swap [Member])	12 Months Ended
	Dec. 31, 2011 bbl
WTI - NYMEX [Member] | Crude Oil [Member] | Jan'12 - Dec'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (in Bbl/day)	5,250
Weighted Average Fixed Price for Swaps	96.54
WTI - NYMEX [Member] | Crude Oil [Member] | Jan'12 - Dec'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jan'12
WTI - NYMEX [Member] | Crude Oil [Member] | Jan'12 - Dec'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Dec'12
WTI - NYMEX [Member] | Crude Oil [Member] | Jan'13 - Dec'13 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (in Bbl/day)	2,000
Weighted Average Fixed Price for Swaps	102.05
WTI - NYMEX [Member] | Crude Oil [Member] | Jan'13 - Dec'13 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jan'13
WTI - NYMEX [Member] | Crude Oil [Member] | Jan'13 - Dec'13 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Dec'13
IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (MMBtu/day)	30,000
Weighted Average Fixed Price for Swaps	5.05
IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jan'12
IF - NYMEX (HH) [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Dec'12
IF - PEPL [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (MMBtu/day)	15,000
Weighted Average Fixed Price for Swaps	5.62
IF - PEPL [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jan'12
IF - PEPL [Member] | Natural Gas [Member] | Jan'12 - Dec'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Dec'12
OPIS - Conway [Member] | Liquids [Member] | Jan'12 - Mar'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (Gal/mo)	1,350,014	[1]
Weighted Average Fixed Price for Swaps	1.10	[1]
OPIS - Conway [Member] | Liquids [Member] | Jan'12 - Mar'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jan'12
OPIS - Conway [Member] | Liquids [Member] | Jan'12 - Mar'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Mar'12
OPIS - Conway [Member] | Liquids [Member] | Apr'12 - Dec'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (Gal/mo)	180,006	[2]
Weighted Average Fixed Price for Swaps	2.11	[2]
OPIS - Conway [Member] | Liquids [Member] | Apr'12 - Dec'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Apr'12
OPIS - Conway [Member] | Liquids [Member] | Apr'12 - Dec'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Dec'12
OPIS - Mont Belvieu [Member] | Liquids [Member] | Jan'12 - Mar'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (Gal/mo)	1,155,018	[1]
Weighted Average Fixed Price for Swaps	0.91	[1]
OPIS - Mont Belvieu [Member] | Liquids [Member] | Jan'12 - Mar'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jan'12
OPIS - Mont Belvieu [Member] | Liquids [Member] | Jan'12 - Mar'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Mar'12
OPIS - Mont Belvieu [Member] | Liquids [Member] | Apr'12 - Jun'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (Gal/mo)	1,000,028	[3]
Weighted Average Fixed Price for Swaps	0.78	[3]
OPIS - Mont Belvieu [Member] | Liquids [Member] | Apr'12 - Jun'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Apr'12
OPIS - Mont Belvieu [Member] | Liquids [Member] | Apr'12 - Jun'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jun'12
OPIS - Mont Belvieu [Member] | Liquids [Member] | Jul'12 - Dec'12 [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Hedged Volume (Gal/mo)	310,000	[4]
Weighted Average Fixed Price for Swaps	0.69	[4]
OPIS - Mont Belvieu [Member] | Liquids [Member] | Jul'12 - Dec'12 [Member] | Start [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Jul'12
OPIS - Mont Belvieu [Member] | Liquids [Member] | Jul'12 - Dec'12 [Member] | End [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Commodity Derivatives Term	Dec'12

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

[2] Types of liquids involved are natural gasoline.

[3] Types of liquids involved are natural gasoline and ethane.

[4] Types of liquids involved are ethane.