Derivative And Financial Instruments (Changes In Fair Value) (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2016 USD ($) item	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	$ (7,726)	$ (5,897)	$ (3,736)	$ (1,064)
Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Beginning fair value of commodity derivatives			31,018	22,829	$ 22,829
Ending fair value of commodity derivatives	14,704		$ 14,704		31,018
Number of counterparties | item			3
Oil [Member] | Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives			$ (3,568)		22,410
Net settlements on derivative contracts			(8,052)		(13,191)
Oil [Member] | Oil And Liquids Sales [Member] | Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	(6,260)	(5,555)	(3,568)	(2,912)
Natural Gas [Member] | Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives			(168)		6,148
Net settlements on derivative contracts			(4,526)		$ (7,178)
Natural Gas [Member] | Natural Gas Sales [Member] | Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	$ (1,466)	$ (342)	$ (168)	$ 1,848