Acquisitions (Summary Of Fair Value Of Assets Acquired And Liabilities Assumed For December 2012 Transferred Properties) (Details) (December 2012 Transferred Properties [Member], USD $)	Dec. 31, 2012	Dec. 28, 2012
December 2012 Transferred Properties [Member]
Business Acquisition [Line Items]
Evaluated		$ 141,315,000
Accumulated depreciation, depletion and amortization		(45,416,000)
Other assets		10,732,000	[1],[2]
Derivative instrument asset, net		(2,948,000)
Long-term debt		(115,000,000)
Asset retirement obligation		(34,261,000)
Book value of net assets		(45,578,000)
Purchase price adjustment	5,300,000	5,270,000
Net assets (liabilities) acquired		$ (40,308,000)

[1] Represents a reclamation deposit in escrow as security for abandonment and redemption obligations.

[2] The net assets contributed to us include the historical book value of the Predecessor as prescribed by our accounting policy for transactions between entities under common control in Note 2 - Summary of Significant Accounting Policies and a $5.3 million purchase price adjustment related to novated derivatives unwound by the Partnership.