Oil and Gas Producing Activities (Unaudited) (Details) bbl in Thousands, MMcf in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2016 USD ($) $ / bbl $ / MMcf bbl MMcf	Dec. 31, 2015 USD ($) $ / bbl $ / MMcf bbl MMcf	Dec. 31, 2014 USD ($) $ / bbl $ / MMcf bbl MMcf	Dec. 31, 2016 USD ($) bbl MMcf	Dec. 31, 2015 USD ($) bbl MMcf	Dec. 31, 2014 USD ($) bbl MMcf
Property acquisition costs [Abstract]
Unproved	$ 32	$ 348	$ 1,144
Proved	0	0	0
Exploration costs [Abstract]
Expensed	291	1,667	5,054
Capitalized	0	0	0
Development costs	0	370	1,745
Total costs incurred	$ 323	2,385	7,943
Capitalized costs relating to oil and gas producing activities [Abstract]
Unproved oil and gas properties				$ 0	$ 231
Proved oil and gas properties				62,784	76,886
Gross capitalized cost				62,784	77,117
Accumulated depreciation, depletion and amortization				(56,426)	(69,116)
Net capitalized cost				6,358	8,001
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				17,938	23,040	$ 58,885
Future costs [Abstract]
Lease operating expenses				(12,421)	(14,524)	(16,421)
Development costs				(38)	(103)	(1,068)
Future net cash flows before income taxes				5,479	8,413	41,396
Discount at 10% per annum				(2,002)	(2,987)	(17,175)
Discounted future net cash flows before income taxes				3,477	5,426	24,221
Future income taxes, net of discount at 10% per annum				(1,217)	(1,899)	(8,477)
Standardized measure of discounted future net cash flows	$ 3,527	3,527	15,744	2,260	3,527	15,744
Effect of income taxes and discounting on the standardized measure of discounted future net cash flows [Abstract]
Future net cash flows before income taxes				5,479	8,413	41,396
Future income taxes				(1,918)	(2,945)	(14,489)
Future net cash flows				3,561	5,468	26,907
Discount at 10% per annum				(1,301)	(1,941)	(11,163)
Standardized measure of discounted future net cash flows	3,527	3,527	15,744	$ 2,260	$ 3,527	$ 15,744
Principal sources of changes in the standardized measure of discounted future net flows [Abstract]
Beginning of year	3,527	15,744	17,836
Sale of oil and gas reserves	(350)	(54)	(981)
Net change in prices and production costs	(1,391)	(17,622)	(72)
New field discoveries and extensions, net of future production costs	275	292	4,456
Sales of oil and gas produced, net of production costs	87	1,038	(6,590)
Net change due to revisions in quantity estimates	181	38	2,460
Accretion of discount	194	1,116	1,773
Production rate changes and other	(945)	(3,603)	(4,265)
Net change in income taxes	682	6,578	1,127
End of year	2,260	3,527	15,744
Results of operations for oil and gas producing activities [Abstract]
Revenues	3,410	5,063	13,361
Costs and expenses [Abstract]
Production	(3,337)	(7,022)	(6,771)
Producing property impairment	(30)	(10,324)	(4,001)
Exploration	0	(1,667)	(5,054)
Oil and natural gas property sale gain	0	0	2,528
Depreciation, depletion and amortization	(1,546)	(5,066)	(7,573)
Operating income (loss) before income taxes	(1,503)	(19,016)	(7,510)
Income tax benefit	526	6,656	2,628
Operating income (loss)	$ (977)	$ (12,360)	$ (4,882)
Oil [Member]
Total proved reserves [Abstract]
Beginning of year | bbl	226	318	368
Revisions of previous estimates | bbl	24	(2)	6
Oil and gas reserves sold | bbl	(4)	(3)	(11)
Extensions, discoveries and other reserve additions | bbl	18	13	82
Production | bbl	(77)	(100)	(127)
End of year | bbl	187	226	318
Components of proved oil and gas reserves [Abstract]
Proved developed reserves | bbl				187	223	299
Proved undeveloped reserves | bbl				0	3	19
Total proved reserves | bbl	226	318	368	187	226	318
Natural Gas [Member]
Total proved reserves [Abstract]
Beginning of year | MMcf	4,835	5,611	6,286
Revisions of previous estimates | MMcf	65	27	724
Oil and gas reserves sold | MMcf	(175)	0	(558)
Extensions, discoveries and other reserve additions | MMcf	151	86	292
Production | MMcf	(662)	(889)	(1,133)
End of year | MMcf	4,214	4,835	5,611
Components of proved oil and gas reserves [Abstract]
Proved developed reserves | MMcf				4,214	4,813	5,482
Proved undeveloped reserves | MMcf				0	22	129
Total proved reserves | MMcf	4,835	4,835	5,611	4,214	4,835	5,611
Crude Oil [Member]
Market Price [Abstract]
Average sales prices | $ / bbl	38.34	45.83	89.60
Natural Gas [Member]
Market Price [Abstract]
Average sales prices | $ / MMcf	2.56	2.62	5.42