Acquisitions (2013 East Texas Acquisition And Other Acquisitions) (Narrative) (Details) (USD $)	12 Months Ended			3 Months Ended	0 Months Ended	3 Months Ended	12 Months Ended	3 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013 2013 Other Acquisitions [Member]	Aug. 06, 2013 2013 East Texas Properties [Member] MMBoe	Dec. 31, 2013 2013 East Texas Properties [Member]	Dec. 31, 2013 2013 East Texas Properties [Member]	Dec. 31, 2013 ETSWDC [Member] 2013 East Texas Properties [Member]	Aug. 06, 2013 ETSWDC [Member] 2013 East Texas Properties [Member]	Aug. 04, 2013 ETSWDC [Member] 2013 East Texas Properties [Member]
Business Acquisition [Line Items]
Date of acquisition							Aug. 06, 2013
Aggregate purchase price				$ 22,600,000	$ 107,800,000
Proved developed reserves					5.9
Effective date of acquisition							Jun. 01, 2013
Cost associated with acquisition recorded in acquisition and transaction costs							400,000
Ownership percentage								59.00%		24.00%
Environmental liability						500,000	500,000
Total revenue	455,629,000	371,998,000	360,904,000			60,000,000
Operating expenses	346,726,000	301,657,000	269,128,000			15,200,000
Percentage of voting interest acquired								3.00%	32.00%
Gain from remeasurement of previous ownership								$ 1,300,000