Summary of Significant Accounting Policies (Details) (USD $)	6 Months Ended		12 Months Ended
	Jun. 30, 2014 mi	Jun. 30, 2013	Dec. 31, 2013	Dec. 31, 2012
Nature of Operations and Principles of Consolidation [Abstract]
Primary area of operation (in miles)	1,000
Components of prepayments and other [Abstract]
Cash collateral deposits for commodity purchases	$ 17,038,000		$ 13,705,000
Insurance premiums	2,911,000		2,490,000
Rents, license and other	1,365,000		584,000
Prepayments, total	21,314,000		16,779,000
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	4,804,000		4,906,000
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	405,000	242,000
Cash Deposits and Other Assets [Abstract]
Insurance collateral deposits	4,432,000		3,718,000
State collateral deposits	183,000		160,000
Materials and supplies	559,000		609,000
Cash deposits and other	5,174,000		4,487,000
Revenue Recognition [Abstract]
Increase in the entity's reported revenue	782,601,000	714,489,000
Concentration of Credit Risk [Line Items]
Maximum percentage of US demand supplied by company (in hundredths)	1.00%
Statement of Cash Flows [Abstract]
Interest paid	0	23,000
Income taxes paid	8,253,000	7,739,000
Non-cash investing activities for property and equipment	846,000	2,468,000	1,507,000	2,419,000
Earnings Per Share [Abstract]
Weighted average number of shares outstanding (in shares)	4,217,596		4,217,596
Commodity Contract [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Number of contracts held	3		1
Commodity Contract [Member] | Not Designated as Hedging Instrument [Member] | Current Assets [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Asset Derivatives	176,000		449,000
Liability Derivatives	0		0
Less Counterparty Offsets	0		(54,000)
As Reported Fair Value Contracts	176,000		395,000
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
Liability Derivatives	0		0
Less Counterparty Offsets	0		0
As Reported Fair Value Contracts	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
Liability Derivatives	112,000		54,000
Less Counterparty Offsets	0		(54,000)
As Reported Fair Value Contracts	112,000		0
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
Liability Derivatives	0		0
Less Counterparty Offsets	0		0
As Reported Fair Value Contracts	0		0
Commodity Contract [Member] | Jan 2014 to Feb 2014 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels or mmbtu)			175
Commodity Contract [Member] | July and August 2014 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels or mmbtu)	433
Commodity Contract [Member] | September 2014 through 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 or mmbtu)	258
Commodity Contract [Member] | March 2015 [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Volume committed per day under commodity purchase and sale contract (in barrels or mmbtu)	129
Commodity Put Option [Member]
Fair Value Forward Hydrocarbon Commodity Contracts at Gross Valuation [Abstract]
Number of contracts held			1
Volume of crude oil committed under commodity put option (in barrels)			100,000
Wells Fargo Bank [Member]
Letter of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	60,000,000
Standby letters of credit issued	13,100,000		14,600,000
Covenant terms	Such restrictions include the maintenance of a combined 1.1 to 1.0 current ratio and the maintenance of positive net earnings excluding inventory valuation changes, as defined, among other restrictions. The Company is currently in compliance with all such financial covenants.
Current ratio	1.1
Revenue [Member]
Concentration of Credit Risk [Line Items]
Percentage of revenues from one customer which loss would not have material effect (in hundredths)	10.00%
Revenue [Member] | Customer Concentration Risk [Member]
Concentration of Credit Risk [Line Items]
Concentration risk, percentage (in hundredths)	50.00%
Concentration risk, additional characteristic	Large crude oil refining concerns
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 (in hundredths)	95.00%
Concentration risk, additional characteristic	Crude oil and natural gas marketing activities
Minimum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years
Minimum [Member] | Customer Concentration Risk [Member]
Concentration of Credit Risk [Line Items]
Number of customers	3
Maximum [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	20 years
Maximum [Member] | Customer Concentration Risk [Member]
Concentration of Credit Risk [Line Items]
Number of customers	4
Producing Oil and Gas Properties [Member]
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	0	142,000
Non-Producing Oil and Gas Properties [Member]
Property, Plant and Equipment [Line Items]
Capitalized costs for non producing oil and gas leasehold interests specified as percentage of total costs (in hundredths)	4.00%
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Impairment	405,000	100,000
South Texas Project acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	4,185,000		4,217,000
West Texas Project acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	14,000		116,000
Napoleonville, Louisiana acreage [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	48,000		162,000
Other acreage areas [Member]
Property, Plant and Equipment [Line Items]
Total Non-producing Leasehold Costs	557,000		411,000
Fair value measurements for oil and gas properties that were subject to fair value impairment [Abstract]
Net book value January 1	411,000	329,000	329,000
Property additions	183,000		304,000
Impairment	(37,000)		(222,000)
Net book value end of period	$ 557,000		$ 411,000
Onshore leasehold [Member]
Property, Plant and Equipment [Line Items]
Property and equipment, useful life	3 years