Property, Plant And Equipment (Schedule Of Property, Plant And Equipment) (Details) $ in Thousands	3 Months Ended			6 Months Ended	9 Months Ended
	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2015 $ / unit Rate	Sep. 30, 2015 USD ($) $ / unit Rate	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Property, Plant and Equipment [Line Items]
Subject to depletion	$ 5,687,844				$ 5,687,844		$ 5,821,167
Unevaluated costs	21,377				21,377		18,803
Accumulated depletion	(5,367,733)				(5,367,733)		(5,225,302)
Net oil and gas properties	341,488				341,488		614,668
Pipelines and processing facilities	293,859				293,859		316,013
General properties	63,288				63,288		66,455
Accumulated depreciation	(257,815)				(257,815)		(268,356)
Net other property and equipment	99,332				99,332		114,112
Property, plant and equipment, net of accumulated depletion and depreciation	440,820				440,820		728,780
Impairment of Oil and Gas Properties	164,518		$ 135		$ 241,929	$ 135
trailing 12-month Henry Hub avg. price | $ / unit					3.06
Percentage Drop In Henry Hub Price | Rate					30.00%
Trailing 12-month AECO average price | $ / unit				2.90	2.51
Percentage Drop in AECO Price | Rate				31.00%	41.00%
UNITED STATES
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net of accumulated depletion and depreciation	266,992				$ 266,992		416,901
Impairment of Oil and Gas Properties	150,816		0		150,816	0
CANADA
Property, Plant and Equipment [Line Items]
Property, plant and equipment, net of accumulated depletion and depreciation	146,960				146,960		$ 280,830
Impairment of Oil and Gas Properties	$ 13,702	$ 77,400	$ 0		$ 91,113	$ 0