Summary of Significant Accounting Policies (Details) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015 USD ($) Contract	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($) BarrelsofOilPerDay Customer Contract shares	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($) Contract shares	Dec. 31, 2013 USD ($)
Components of Prepayments and Other [Abstract]
Cash collateral deposits for commodity purchases	$ 4,055		$ 4,055		$ 7,872
Insurance premiums	2,162		2,162		2,316
Rents, license and other	933		933		752
Prepayments, total	7,150		7,150		10,940
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	614		614		959
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	568	$ 168	1,191	$ 572
Cash Deposits and Other Assets [Abstract]
Insurance collateral deposits	5,413		5,413		4,536
State collateral deposits	154		154		155
Materials and supplies	339		339		307
Cash deposits and other	5,906		5,906		4,998
Revenue Recognition [Abstract]
Revenue gross-up	122,273	271,749	$ 388,936	1,054,350
Concentration of Credit Risk [Line Items]
Maximum percentage of US demand supplied by company			1.00%
Statement of Cash Flows [Abstract]
Interest paid	1	2	$ 5	2
Taxes paid (refund)	2,431	(113)	4,038	8,140
Property and equipment additions			$ 3	3,315	$ 1,137	$ 1,507
Earnings Per Share [Abstract]
Weighted average number of shares outstanding (in shares) | shares			4,217,596		4,217,596
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			3 years
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life			20 years
Customer Concentration Risk [Member] | Minimum [Member]
Concentration of Credit Risk [Line Items]
Number of customers | Customer			3
Customer Concentration Risk [Member] | Maximum [Member]
Concentration of Credit Risk [Line Items]
Number of customers | Customer			4
Producing Property Impairments [Member]
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	$ 0	0	$ 207	0
Non-Producing Property Impairments [Member]
Property, Plant and Equipment [Line Items]
Capitalized costs for non-producing oil and gas leasehold interests specified as percentage of total costs	4.00%		4.00%
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	$ 568	$ 168	$ 984	572
South Texas Project Acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	358		358		$ 357
Napoleonville, Louisiana Acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	49		49		48
North Dakota and Other Acreage Areas [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	207		207		554
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Net book value January 1			554	$ 411	411
Property additions			68		580
Impairment			(415)		(437)
Net book value end of period	207		$ 207		554	$ 411
Onshore Leasehold [Member]
Property, Plant and Equipment [Line Items]
Onshore Leasehold Period			3 years
Wells Fargo Bank [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	60,000		$ 60,000
Stand-by letters of credit	$ 1,000		$ 1,000		$ 15,300
Current ratio			1.1
Commodity Contract [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Number of contracts held | Contract	2		2		3
Commodity Contract [Member] | October 2015 through December 31, 2015 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels per day) | BarrelsofOilPerDay			129
Commodity Contract [Member] | January and February 2015 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels per day) | BarrelsofOilPerDay			294
Commodity Contract [Member] | March through December 2015 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels per day) | BarrelsofOilPerDay			129
Commodity Contract [Member] | October 2015 through March 2016 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels per day) | BarrelsofOilPerDay			65
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Asset Derivatives	$ 363		$ 363		$ 1,332
Liability Derivatives	0		0		0
Less Counterparty Offsets	(171)		(171)		(396)
Net Value	192		192		936
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Assets [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Asset Derivatives	0		0		0
Liability Derivatives	0		0		0
Less Counterparty Offsets	0		0		0
Net Value	0		0		0
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Liabilities [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Asset Derivatives	0		0		0
Liability Derivatives	528		528		1,339
Less Counterparty Offsets	(171)		(171)		(396)
Net Value	357		357		943
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Other Liabilities [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Asset Derivatives	0		0		0
Liability Derivatives	0		0		0
Less Counterparty Offsets	0		0		0
Net Value	$ 0		$ 0		$ 0
Revenue [Member]
Concentration of Credit Risk [Line Items]
Percentage of revenues from one customer which loss would not have material effect			10.00%
Revenue [Member] | Customer Concentration Risk [Member]
Concentration of Credit Risk [Line Items]
Concentration risk, percentage			50.00%
Accounts Receivable [Member]
Concentration of Credit Risk [Line Items]
Industry practice payment of receivables			20 days
Accounts Receivable [Member] | Product Concentration Risk [Member]
Concentration of Credit Risk [Line Items]
Concentration risk, percentage			90.00%