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Supplemental Oil And Gas Information (Schedule Of Changes In The Standardized Measure Of Discounted Future Net Cash Flows From Proved Oil And Gas Reserves) (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Supplemental Oil And Gas Information [Abstract] |  |  |
Balance, beginning of year | $ 34,531 | $ 38,708 | $ 45,354
Sales, net of production costs and taxes | (1,901) | (8,385) | (10,471)
Discoveries and extensions, net of costs | 5 | 4,231 | 4,047
Sale of reserves in place |  |  | (767)
Net changes in prices and production costs | (16,009) | (829) | (1,277)
Revisions of quantity estimates | (22,431) | (6,610) | (4,306)
Previously estimated development cost incurred during the year |  | 508 | 3,149
Changes in future development costs | 4,890 | (1,913) | (1,392)
Changes in production rates (timing) and other | (56) | 1,312 | 368
Accretion of discount | 3,373 | 4,247 | 4,593
Net change in income taxes | 5,885 | 3,262 | (590)
Balance, end of year | $ 8,287 | $ 34,531 | $ 38,708

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- Definition Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of passage of time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 35 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62500-109447 + Details
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- Definition Amount of decrease in standardized measure of discounted future net cash flow as a result of sales of minerals in place. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 35 -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62500-109447 + Details
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- Definition Amount of increase (decrease) in standardized measure of discounted future net cash flow as a result of extensions, discoveries and improved recovery of proved oil and gas reserves. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 932 -SubTopic 235 -Section 50 -Paragraph 35 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=8451039&loc=d3e62500-109447 + Details
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