Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) - Natural Gas [Member] - Level 3 [Member] - Three-way collar [Member] $ in Thousands	Mar. 31, 2020 USD ($) $ / Unit
Derivative fair value | $	$ 948	[1]
Minimum [Member]
Forward commodity price curve	0
Maximum [Member]
Forward commodity price curve	0.86

[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 paid or received within the settlement period.