XML 76 R64.htm IDEA: XBRL DOCUMENT v3.8.0.1
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
Dec. 31, 2017
Dec. 31, 2016
Dec. 31, 2015
Supplemental Oil And Gas Information [Abstract]      
Balance, beginning of year $ 5,815 $ 8,287 $ 34,531
Sales, net of production costs and taxes (1,239) (2,037) (1,901)
Discoveries and extensions, net of costs 123 35 5
Purchase of reserves in place
Sale of reserves in place (10)
Net changes in prices and production costs 1,780 (863) (16,009)
Revisions of quantity estimates 1,611 (412) (22,431)
Previously estimated development cost incurred during the year
Changes in future development costs (228) 196 4,890
Changes in timing and other (164) (20) (56)
Accretion of discount 472 639 3,373
Net change in income taxes 5,885
Balance, end of year $ 8,170 $ 5,815 $ 8,287