Summary of Significant Accounting Policies (Details)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) mi² Contract bbl	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) mi² BarrelsofOilPerDay Customer Contract shares bbl	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) Contract shares
Nature of Operations and Principles of Consolidation [Abstract]
Primary area of operation (in square miles) | mi²	1,000		1,000
Components of Prepayments [Abstract]
Cash collateral deposits for commodity purchases	$ 0		$ 0		$ 167,000
Insurance premiums	3,323,000		3,323,000		1,609,000
Rents, license and other	836,000		836,000		813,000
Prepayments, total	4,159,000		4,159,000		2,589,000
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	200,000		200,000		231,000
Fair value measurements for producing and non-producing oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	0	$ 568,000	87,000	$ 1,191,000
Cash Deposits and Other Assets [Abstract]
Insurance collateral deposits	5,585,000		5,585,000		6,531,000
State collateral deposits	131,000		131,000		140,000
Materials and supplies	281,000		281,000		292,000
Cash deposits and other	5,997,000		5,997,000		$ 6,963,000
Revenue Recognition [Abstract]
Revenue gross-up	70,236,000	122,273,000	$ 245,245,000	388,936,000
Concentration of Credit Risk [Line Items]
Maximum percentage of US demand supplied by company			1.00%
Statement of Cash Flows [Abstract]
Interest paid			$ 0	5,000
Federal and state tax paid			2,582,000	4,038,000
Property and equipment additions			$ 382,000	3,000
Earnings Per Share [Abstract]
Weighted average number of shares outstanding (in shares) | shares			4,217,596		4,217,596
Potentially dilutive securities (in shares) | shares			0		0
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
As Reported Fair Value Contracts	153,000		$ 153,000		$ 0
As Reported Fair Value Contracts	43,000		$ 43,000		195,000
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			5
Producing Property Impairments [Member]
Fair value measurements for producing and non-producing oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	$ 0	0	$ 1,000	207,000
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	3.00%		3.00%
Fair value measurements for producing and non-producing oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	$ 0	568,000	$ 86,000	984,000
Napoleonville, Louisiana Acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	0		0		49,000
Wyoming and Other Acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	200,000		$ 200,000		$ 182,000
Onshore Leasehold [Member]
Property, Plant and Equipment [Line Items]
Onshore normal leasehold period			3 years
Wells Fargo Bank [Member] | Standby Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	60,000,000		$ 60,000,000
Stand-by letters of credit	$ 0	$ 1,000,000	$ 0	$ 1,000,000
Current ratio			1.1
Commodity Contract [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Number of contracts held | Contract	3		3		1
Commodity Contract [Member] | October 2016 through March 2017 [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] | November 2016 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Total volume committed under commodity purchase and sale contract (in barrels or mmbtu) | bbl	142,000		142,000
Commodity Contract [Member] | October 2016 Through December 2016 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Total volume committed under commodity purchase and sale contract (in barrels or mmbtu) | bbl	3,000		3,000
Commodity Contract [Member] | January 2016 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	$ 153,000		$ 153,000		$ 0
Liability Derivatives	0		0		0
Less Counterparty Offsets	0		0		0
As Reported Fair Value Contracts	153,000		153,000		0
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
As Reported Fair Value Contracts	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	43,000		43,000		195,000
Less Counterparty Offsets	0		0		0
As Reported Fair Value Contracts	43,000		43,000		195,000
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
As Reported Fair Value Contracts	$ 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%
Accounting Standard Update 2016-02 [Member]
Recent Accounting Pronouncement [Abstract]
Long-term non-cancellable operating lease arrangements					$ 12,393,000