Oil and Gas Producing Activities (Unaudited) (Details) bbl in Thousands, MMcf in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) $ / MMcf $ / bbl bbl MMcf	Dec. 31, 2014 USD ($) $ / MMcf $ / bbl bbl MMcf	Dec. 31, 2013 USD ($) $ / MMcf $ / bbl bbl MMcf	Dec. 31, 2015 USD ($) bbl MMcf	Dec. 31, 2014 USD ($) bbl MMcf	Dec. 31, 2013 USD ($) bbl MMcf
Property acquisition costs [Abstract]
Unproved	$ 348	$ 1,144	$ 1,444
Proved	0	0	0
Exploration costs [Abstract]
Expensed	1,667	5,054	1,619
Capitalized	0	0	0
Development costs	370	1,745	10,160
Total costs incurred	$ 2,385	7,943	13,223
Capitalized costs relating to oil and gas producing activities [Abstract]
Unproved oil and gas properties				$ 231	$ 3,104
Proved oil and gas properties				76,886	85,557
Gross capitalized cost				77,117	88,661
Accumulated depreciation, depletion and amortization				(69,116)	(64,682)
Net capitalized cost				8,001	23,979
Components of proved oil and gas reserves [Abstract]
Period of average estimated price of proved reserves	12 months
Standardized measure of discounted future net cash flows [Abstract]
Future gross revenues				23,040	58,885	$ 64,495
Future costs [Abstract]
Lease operating expenses				(14,524)	(16,421)	(19,207)
Development costs				(103)	(1,068)	(119)
Future net cash flows before income taxes				8,413	41,396	45,169
Discount at 10% per annum				(2,987)	(17,175)	(17,729)
Discounted future net cash flows before income taxes				5,426	24,221	27,440
Future income taxes, net of discount at 10% per annum				(1,899)	(8,477)	(9,604)
Standardized measure of discounted future net cash flows	$ 3,527	15,744	17,836	3,527	15,744	17,836
Effect of income taxes and discounting on the standardized measure of discounted future net cash flows [Abstract]
Future net cash flows before income taxes				8,413	41,396	45,169
Future income taxes				(2,945)	(14,489)	(15,809)
Future net cash flows				5,468	26,907	29,360
Discount at 10% per annum				(1,941)	(11,163)	(11,524)
Standardized measure of discounted future net cash flows	3,527	15,744	17,836	$ 3,527	$ 15,744	$ 17,836
Principal sources of changes in the standardized measure of discounted future net flows [Abstract]
Beginning of year	15,744	17,836	16,355
Sale of oil and gas reserves	(54)	(981)	0
Net change in prices and production costs	(17,622)	(72)	9,341
New field discoveries and extensions, net of future production costs	292	4,456	9,767
Sales of oil and gas produced, net of production costs	1,038	(6,590)	(8,373)
Net change due to revisions in quantity estimates	38	2,460	(3,624)
Accretion of discount	1,116	1,773	1,797
Production rate changes and other	(3,603)	(4,265)	(6,629)
Net change in income taxes	6,578	1,127	(798)
End of year	3,527	15,744	17,836
Results of operations for oil and gas producing activities [Abstract]
Revenues	5,063	13,361	14,129
Costs and expenses [Abstract]
Production	(7,022)	(6,771)	(5,756)
Producing property impairment	(10,324)	(4,001)	(1,373)
Exploration	(1,667)	(5,054)	(1,619)
Oil and natural gas property sale gain	0	2,528	0
Depreciation, depletion and amortization	(5,066)	(7,573)	(7,494)
Operating income (loss) before income taxes	(19,016)	(7,510)	(2,113)
Income tax benefit	6,656	2,628	739
Operating income (loss)	$ (12,360)	$ (4,882)	$ (1,374)
Oil [Member]
Total proved reserves [Abstract]
Beginning of year | bbl	318	368	307
Revisions of previous estimates | bbl	(2)	6	(17)
Oil and gas reserves sold | bbl	(3)	(11)	0
Extensions, discoveries and other reserve additions | bbl	13	82	180
Production | bbl	(100)	(127)	(102)
End of year | bbl	226	318	368
Components of proved oil and gas reserves [Abstract]
Proved developed reserves | bbl				223	299	367
Proved undeveloped reserves | bbl				3	19	1
Total proved reserves | bbl	318	318	307	226	318	368
Natural Gas [Member]
Total proved reserves [Abstract]
Beginning of year | MMcf	5,611	6,286	8,837
Revisions of previous estimates | MMcf	27	724	(1,438)
Oil and gas reserves sold | MMcf	0	(558)	(28)
Extensions, discoveries and other reserve additions | MMcf	86	292	523
Production | MMcf	(889)	(1,133)	(1,608)
End of year | MMcf	4,835	5,611	6,286
Components of proved oil and gas reserves [Abstract]
Proved developed reserves | MMcf				4,813	5,482	6,157
Proved undeveloped reserves | MMcf				22	129	129
Total proved reserves | MMcf	5,611	6,286	6,286	4,835	5,611	6,286
Crude Oil [Member]
Market Price [Abstract]
Average sales prices | $ / bbl	45.83	89.60	94.99
Natural Gas [Member]
Market Price [Abstract]
Average sales prices | $ / MMcf	2.62	5.42	4.69