Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) - Level 3 [Member] $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) $ / Unit
Oil [Member] | Three-way collar [Member]
Derivative fair value | $	$ 3,096
Unobservable Input	Forward commodity price curve
Oil [Member] | Three-way collar [Member] | Minimum [Member]
Forward commodity price curve	0
Oil [Member] | Three-way collar [Member] | Maximum [Member]
Forward commodity price curve	7.93
Natural Gas [Member] | Collar [Member]
Derivative fair value | $	$ (16)
Unobservable Input	Forward commodity price curve
Natural Gas [Member] | Collar [Member] | Minimum [Member]
Forward commodity price curve	0
Natural Gas [Member] | Collar [Member] | Maximum [Member]
Forward commodity price curve	0.130