Derivative And Financial Instruments (Change In Fair Value) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	$ 25,150	$ 19,854
Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Beginning fair value of commodity derivatives	22,829	10,601
Ending fair value of commodity derivatives	31,018	22,829
Oil [Member] | Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	22,410	13,983
Net settlements on derivative contracts	(13,191)	69
Oil [Member] | Oil And Liquids Sales [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	19,147	19,854
Natural Gas [Member] | Commodity Contract [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	6,148	5,871
Net settlements on derivative contracts	(7,178)	$ (7,695)
Natural Gas [Member] | Natural Gas Sales [Member]
Derivative Instruments Gain Loss [Line Items]
Net gains (losses) on derivatives	$ 6,003