Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) (Level 3 [Member], Collar [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012
Derivative assets, Fair Value	$ (595)	[1]
Derivatives assets, Valuation Technique(s)	Discounted cash flow	[1]
Unobservable Input	Forward commodity price curve	[1]
Minimum [Member]
Forward commodity price curve	0.09
Maximum [Member]
Forward commodity price curve	0.56

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