Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) (Level 3 [Member], Commodity Contract [Member], USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2012
Derivative assets, Fair Value	$ 8,130	[1]
Derivatives assets, Valuation Technique(s)	Discounted cash flow	[1]
Unobservable Input	Forward commodity price curve	[1]
Minimum [Member]
Forward commodity price curve	2.64
Maximum [Member]
Forward commodity price curve	3.22

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