Fair Value Measurements (Schedule Of Quantitative Information About Unobservable Inputs) (Details) - Level 3 $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) $ / Unit
Crude Oil | Three-way collar
Fair Value | $	$ 10,592	[1]
Valuation Technique(s)	Discounted cash flow	[1]
Unobservable Input	Forward commodity price curve	[1]
Crude Oil | Minimum | Three-way collar
Average Forward Price	0
Crude Oil | Maximum | Three-way collar
Average Forward Price	19.44
Natural gas | Collar
Fair Value | $	$ (334)	[1]
Valuation Technique(s)	Discounted cash flow	[1]
Unobservable Input	Forward commodity price curve	[1]
Natural gas | Three-way collar
Fair Value | $	$ 372	[1]
Valuation Technique(s)	Discounted cash flow	[1]
Unobservable Input	Forward commodity price curve	[1]
Natural gas | Minimum | Collar
Average Forward Price	0
Natural gas | Minimum | Three-way collar
Average Forward Price	0
Natural gas | Maximum | Collar
Average Forward Price	0.38
Natural gas | Maximum | Three-way collar
Average Forward Price	0.43

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