Derivative Instruments (Schedule Of Derivative Assets And Liabilities Statement) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Derivative asset, fair value, gross asset	$ 4,848	$ 2,673
Derivative liability, fair value, gross liability	49,647	74,299
Derivatives Designated as Cash Flow Hedges [Member]
Derivative asset, fair value, gross asset	4,539	2,673
Derivative liability, fair value, gross liability	10,128	14,692
Derivatives Not Designated as Cash Flow Hedges [Member]
Derivative asset, fair value, gross asset	309	0
Derivative liability, fair value, gross liability	39,519	59,607
Current [Member] | Derivatives Designated as Cash Flow Hedges [Member] | Commodity Derivatives [Member]
Derivative asset, fair value, gross asset	4,065	2,650
Derivative liability, fair value, gross liability	10,065	11,421
Current [Member] | Derivatives Not Designated as Cash Flow Hedges [Member] | Ethane - Put Options [Member]
Derivative asset, fair value, gross asset	309	0
Derivative liability, fair value, gross liability	0	0
Current [Member] | Derivatives Not Designated as Cash Flow Hedges [Member] | Interest Rate [Member]
Derivative asset, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	470	1,751
Long Term [Member] | Derivatives Designated as Cash Flow Hedges [Member] | Commodity Derivatives [Member]
Derivative asset, fair value, gross asset	474	23
Derivative liability, fair value, gross liability	63	3,271
Long Term [Member] | Derivatives Not Designated as Cash Flow Hedges [Member] | Interest Rate [Member]
Derivative asset, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	0	833
Long Term [Member] | Derivatives Not Designated as Cash Flow Hedges [Member] | Embedded Derivatives [Member]
Derivative asset, fair value, gross asset	0	0
Derivative liability, fair value, gross liability	$ 39,049	$ 57,023