Supplemental Oil And Gas Disclosures (Schedule Of Proved Developed And Undeveloped Oil And Gas Reserve Quantities) (Details)	12 Months Ended
	Dec. 31, 2014 bbl		Dec. 31, 2013 bbl		Dec. 31, 2012 bbl
Oil (bbls)
Proved developed and undeveloped reserves:
Beginning of year	21,765,000		21,998,000		20,255,000
Revision of previous estimates	(3,174,000)	[1]	(2,113,000)	[1]	(1,747,000)	[1]
Extensions and discoveries	5,327,000		4,678,000		5,014,000
Infill reserves in existing proved fields	2,775,000		2,299,000		4,196,000
Purchases of minerals in place	236,000		0		2,830,000
Production	(3,844,000)		(3,360,000)		(3,279,000)
Sales	(418,000)		(1,737,000)		(5,271,000)
End of year	22,667,000		21,765,000		21,998,000
Proved developed reserves:
Beginning of year	15,594,000		16,441,000		15,618,000
End of year	17,448,000		15,594,000		16,441,000
Proved undeveloped reserves
Beginning of year	6,171,000		5,557,000		4,637,000
End of year	5,219,000		6,171,000		5,557,000
Natural Gas Liquids (bbls)
Proved developed and undeveloped reserves:
Beginning of year	41,205,000		35,166,000		22,087,000
Revision of previous estimates	(2,266,000)	[1]	836,000	[1]	(2,682,000)	[1]
Extensions and discoveries	10,850,000		7,273,000		4,819,000
Infill reserves in existing proved fields	3,577,000		1,945,000		3,018,000
Purchases of minerals in place	88,000		0		11,098,000
Production	(4,629,000)		(3,914,000)		(2,796,000)
Sales	(296,000)		(101,000)		(378,000)
End of year	48,529,000		41,205,000		35,166,000
Proved developed reserves:
Beginning of year	30,437,000		25,657,000		16,649,000
End of year	35,850,000		30,437,000		25,657,000
Proved undeveloped reserves
Beginning of year	10,768,000		9,509,000		5,438,000
End of year	12,679,000		10,768,000		9,509,000
Natural Gas (Mcf)
Proved developed and undeveloped reserves:
Beginning of year	581,784,000		555,647,000		442,135,000
Revision of previous estimates	(32,790,000)	[1]	2,421,000	[1]	(55,110,000)	[1]
Extensions and discoveries	113,541,000		68,611,000		54,761,000
Infill reserves in existing proved fields	47,189,000		21,573,000		25,057,000
Purchases of minerals in place	368,000		11,000		141,494,000
Production	(58,854,000)		(56,757,000)		(48,930,000)
Sales	(4,277,000)		(9,722,000)		(3,760,000)
End of year	646,961,000		581,784,000		555,647,000
Proved developed reserves:
Beginning of year	464,234,000		452,844,000		372,311,000
End of year	500,950,000		464,234,000		452,844,000
Proved undeveloped reserves
Beginning of year	117,550,000		102,803,000		69,824,000
End of year	146,011,000		117,550,000		102,803,000

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