Supplemental Information On Oil And Natural Gas Producing Activities (Capitalized Costs) (Details) - USD ($) $ in Thousands		Dec. 31, 2016	Dec. 31, 2015
Supplemental Information On Oil And Natural Gas Producing Activities
Proved property	[1]	$ 758,366	$ 731,548
Unproved property	[1]	46	39
Land		501	501
Total property costs	[1]	758,913	732,088
Materials and supplies	[1]	1,056	1,056
Total	[1]	759,969	733,144
Less: accumulated depreciation, depletion, amortization and impairments	[1]	(674,338)	(652,167)
Oil and natural gas properties and equipment, net	[1]	$ 85,631	$ 80,977

[1] Capitalized costs include the cost of equipment and facilities for our oil and natural gas producing activities. Proved property costs include capitalized costs for leaseholds holding proved reserves; development wells and related equipment and facilities (including uncompleted development well costs); and support equipment. Unproved property costs include capitalized costs for oil and natural gas leaseholds where proved reserves do not exist.