Summary Of Significant Accounting Policies (Summary Of The Activity For Company's Decommissioning Liabilities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Summary Of Significant Accounting Policies [Abstract]
Decommissioning liabilities, December 31, 2014 and 2013, respectively	$ 88,000	$ 83,519
Liabilities acquired and incurred	266	866
Liabilities settled		(579)
Accretion	5,016	4,470
Revision in estimated liabilities	24,660	(276)
Total decommissioning liabilities, December 31, 2015 and 2014, respectively	$ 88,000	$ 83,519	$ 117,942	$ 88,000
Less: current portion of decommissioning liabilities as of December 31, 2015 and 2014, respectively			19,052
Long-term decommissioning liabilities, December 31, 2015 and 2014, respectively			$ 98,890	$ 88,000