Disclosure About Oil and Gas Producing Activities (Unaudited) (Narratives) (Details)	12 Months Ended
	Dec. 31, 2015 USD ($) Bcfe Tcfe	Dec. 31, 2013 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2011 Bcfe Tcfe
Oil And Gas Exploration And Production Industries Disclosures [Abstract]
Internal Engineer Experience	14
Reserves Prepared Internally		2.00%
Expert Qualfications	The reserves estimates shown herein have been independently evaluated by NSAI, a worldwide leader of petroleum property analysis for industry and financial organizations and government agencies.  NSAI was founded in 1961 and performs consulting petroleum engineering services under Texas Board of Professional Engineers Registration No. F-2699.  Within NSAI, the technical persons primarily responsible for preparing the estimates set forth in the NSAI reserves report incorporated herein are Mr. Robert C. Barg and Mr. Phillip R. Hodgson.  Mr. Barg, a Licensed Professional Engineer in the State of Texas (No. 71658), has been practicing consulting petroleum engineering at NSAI since 1989 and has over 6 years of prior industry experience.  He graduated from Purdue University in 1983 with a Bachelor of Science Degree in Mechanical Engineering.  Mr. Hodgson, a Licensed Professional Geoscientist in the State of Texas (No. 1314), has been practicing consulting petroleum geoscience at NSAI since 1998 and has over 14 years of prior industry experience.  He graduated from University of Illinois in 1982 with a Bachelor of Science Degree in Geology and from Purdue University in 1984 with a Master of Science Degree in Geophysics.  Both technical principals meet or exceed the education, training, and experience requirements set forth in the Standards Pertaining to the Estimating and Auditing of Oil and Gas Reserves Information promulgated by the Society of Petroleum Engineers; both are proficient in judiciously applying industry standard practices to engineering and geoscience evaluations as well as applying SEC and other industry reserves definitions and guidelines.
Proved Undeveloped Reserve Changes [Abstract]
Proved Undeveloped Reserve Conversions | Bcfe	516.2
Proved Undeveloped Reserve Conversion Rate	18.00%
Proved Undeveloped Reserve Transfers To Unproven | Tcfe	2.4
Total Proved Reserves Equivalent | Tcfe				5
Proved Undeveloped Resesrves Reclassified in Pennsylvania | Bcfe				106
Weighted Average Sales Price For Proved Reserves Textuals [Abstract]
Weighted Average Sales Price For Proved Reserves Natural Gas	$ 2.21	$ 3.51	$ 4.32
Weighted Average Sales Price For Proved Reserves Condensate	42.36	84.97	80.62
Weighted Average Sales Price For Proved Reserves Natural Gas Liquids	$ 20.61	$ 0	$ 46.27