Supplemental Oil And Gas Information (Schedule Of Standardized Measure Of Discounted Futures Net Cash Flows From Proved Oil And Gas Reserves) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Supplemental Oil And Gas Information [Abstract]
Future cash inflows	$ 158,792	$ 183,801	$ 194,941
Future production costs and taxes	(71,951)	(82,307)	(82,069)
Future development costs	(10,014)	(11,162)	(7,894)
Future income tax expenses	(13,092)	(18,910)	(19,472)
Future net cash flows	63,735	71,422	85,506
Discount at 10% for timing of cash flows	(29,204)	(32,714)	(40,152)
Standardized measure of discounted future net cash flows	$ 34,531	$ 38,708	$ 45,354