Supplemental Oil And Gas Disclosures (Schedule Of Proved Developed And Undeveloped Oil And Gas Reserve Quantities) (Details) bbl in Thousands, Mcf in Thousands		12 Months Ended
		Dec. 31, 2015 bbl Mcf	Dec. 31, 2014 bbl Mcf	Dec. 31, 2013 bbl Mcf
Oil (bbls)
Proved developed and undeveloped reserves:
Beginning of year		22,667	21,765	21,998
Revision of previous estimates	[1]	(3,954)	(3,174)	(2,113)
Extensions and discoveries		1,208	5,327	4,678
Infill reserves in existing proved fields		670	2,775	2,299
Purchases of minerals in place		0	236	0
Production		(3,783)	(3,844)	(3,360)
Sales		(73)	(418)	(1,737)
End of year		16,735	22,667	21,765
Proved developed reserves:
Beginning of year		17,448	15,594	16,441
End of year		14,679	17,448	15,594
Proved undeveloped reserves
Beginning of year		5,219	6,171	5,557
End of year		2,056	5,219	6,171
Natural Gas Liquids (bbls)
Proved developed and undeveloped reserves:
Beginning of year		48,529	41,205	35,166
Revision of previous estimates	[1]	(9,367)	(2,266)	836
Extensions and discoveries		1,948	10,850	7,273
Infill reserves in existing proved fields		1,861	3,577	1,945
Purchases of minerals in place		0	88	0
Production		(5,274)	(4,629)	(3,914)
Sales		(10)	(296)	(101)
End of year		37,687	48,529	41,205
Proved developed reserves:
Beginning of year		35,850	30,437	25,657
End of year		31,218	35,850	30,437
Proved undeveloped reserves
Beginning of year		12,679	10,768	9,509
End of year		6,469	12,679	10,768
Natural gas (Mcf)
Proved developed and undeveloped reserves:
Beginning of year | Mcf		646,961	581,784	555,647
Revision of previous estimates | Mcf	[1]	(139,514)	(32,790)	2,421
Extensions and discoveries | Mcf		20,974	113,541	68,611
Infill reserves in existing proved fields | Mcf		22,641	47,189	21,573
Purchases of minerals in place | Mcf		0	368	11
Production | Mcf		(65,546)	(58,854)	(56,757)
Sales | Mcf		(648)	(4,277)	(9,722)
End of year | Mcf		484,868	646,961	581,784
Proved developed reserves:
Beginning of year | Mcf		500,950	464,234	452,844
End of year | Mcf		416,395	500,950	464,234
Proved undeveloped reserves
Beginning of year | Mcf		146,011	117,550	102,803
End of year | Mcf		68,473	146,011	117,550

[1] Natural gas revisions of previous estimates decreased primarily due to a decline in natural gas prices.