Summary of Significant Accounting Policies (Details Textual) (USD $)	3 Months Ended			6 Months Ended	9 Months Ended	12 Months Ended												3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2011	Jun. 30, 2012	Sep. 30, 2012	Dec. 31, 2013 Purchasers segment Subsidiaries	Dec. 31, 2013 Subsidiaries	Dec. 31, 2012 Purchasers	Dec. 31, 2012	Dec. 31, 2011 Purchasers	Dec. 31, 2011	Dec. 31, 2013 Machinery and Equipment [Member]	Dec. 31, 2013 Maximum [Member]	Dec. 31, 2010 Maximum [Member]	Dec. 31, 2013 Minimum [Member]	Dec. 31, 2010 Minimum [Member]	Dec. 31, 2013 Class A [Member]	Mar. 31, 2012 Class B [Member]	Dec. 31, 2012 Class B [Member]	Dec. 31, 2011 Class B [Member]	Dec. 31, 2013 Class B [Member] Minimum [Member]	Dec. 31, 2013 Accounts Receivable [Member]	Dec. 31, 2012 Accounts Receivable [Member]	Dec. 31, 2011 Accounts Receivable [Member]	Dec. 31, 2013 Sales Revenue, Goods, Net [Member]	Dec. 31, 2012 Sales Revenue, Goods, Net [Member]	Dec. 31, 2011 Sales Revenue, Goods, Net [Member]	Dec. 31, 2013 Restricted stock [Member]	Dec. 31, 2012 Restricted stock [Member]	Dec. 31, 2011 Restricted stock [Member]	Dec. 31, 2013 Restricted stock [Member] Maximum [Member]	Dec. 31, 2012 Restricted stock [Member] Maximum [Member]	Dec. 31, 2013 Restricted stock [Member] Minimum [Member]	Dec. 31, 2012 Restricted stock [Member] Minimum [Member]	Dec. 31, 2013 Stock options [Member]	Dec. 31, 2012 Stock options [Member]	Dec. 31, 2011 Stock options [Member]	Dec. 31, 2013 Stock options [Member] Maximum [Member]	Dec. 31, 2013 Stock options [Member] Minimum [Member]
Summary of Significant Accounting Policies [Line Items]
Number of wholly owned subsidiaries						4	4
Number of operating segments						1	1
Short-term investments with an original maturity													1 year		30 days
Accounts receivable due period													60 days		30 days
Billing date						30 days	30 days
Outstanding days of account receivable						60 days	60 days
Capitalized general and administrative costs							$ 3,700,000		$ 2,600,000		$ 2,000,000
Capitalized interest expense							1,900,000		1,600,000		1,300,000
Present value discounted percent of future net revenues of proved oil and natural gas reserves						10.00%	10.00%
Average oil and natural gas prices						3.670	93.42	2.757	91.21	92.71	4.118
Net capitalized costs less related deferred income taxes exceeded the full-cost ceiling	13,700,000		23,000,000	21,300,000	2,300,000				17,300,000
Impairment charge of net capitalized costs	21,200,000	26,700,000	35,700,000	33,200,000	3,600,000		21,229,000		63,475,000		35,673,000
Deferred income tax credit	7,500,000		12,700,000	11,900,000	1,300,000				9,400,000
Useful life													10 years	5 years	5 years	3 years
Useful life using the straight-line												30 years
Number of purchasers						5	5	3	3	3	3
Concentration risk, percentage																						81.00%	67.00%	52.00%	87.00%	74.00%	60.00%
Vested Period						4 years	4 years						4 years		3 years													3 years			4 years	4 years	1 year	1 year	3 years			4 years	3 years
Stock-based compensation						0	0
Stock-based compensation (non-cash) expense							3,897,000		140,000		2,406,000																	100,000	100,000	200,000					2,200,000	(700,000)	2,100,000
Common stock and restricted stock unit expense							331,000		100,000		200,000
Percentage being realized up on ultimate settlement						50.00%	50.00%
Cumulative annual dividends per share rate																					$ 0.26
Dividends declared									27,643		274,853								27,643	274,853
Dividends paid																		$ 96,356
Conversion of Class B common stock to Class A common stock, shares																	1,030,700