Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) - Natural gas - Level 3 - Three-way collar $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / Unit
Fair Value | $	$ 1,204	[1]
Unobservable Input	Forward commodity price curve	[1]
Minimum
Average Forward Price	0
Maximum
Average Forward Price	0.39

[1] The commodity contracts detailed in this category include non-exchange-traded natural gas three-way 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.