Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) (Level 3 [Member], Collar [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013
Crude Oil [Member]
Derivative assets, Fair Value	$ 1,781	[1]
Derivatives assets, Valuation Technique(s)	Discounted cash flow
Unobservable Input	Forward commodity price curve
Crude Oil [Member] | Minimum [Member]
Forward commodity price curve	(5.01)
Crude Oil [Member] | Maximum [Member]
Forward commodity price curve	9.44
Natural Gas [Member]
Derivative assets, Fair Value	$ (335)	[1]
Derivatives assets, Valuation Technique(s)	Discounted cash flow
Unobservable Input	Forward commodity price curve
Natural Gas [Member] | Minimum [Member]
Forward commodity price curve	(0.34)
Natural Gas [Member] | Maximum [Member]
Forward commodity price curve	0.10

[1] The commodity contracts detailed in this category include non-exchange-traded natural gas and crude oil collars that are valued based on NYMEX. The forward pricing range represents the low and high price expected to be paid or received within the settlement period.