Significant Accounting Policies (Details Textual) (USD $)	1 Months Ended	3 Months Ended		12 Months Ended
	Jan. 31, 2007	Dec. 31, 2011 Boe	Mar. 31, 2009	Dec. 31, 2011 Y Boe	Dec. 31, 2010	Dec. 31, 2009
Summary of Significant Accounting Policies (Textual) [Abstract]
Total capitalized internal costs				$ 29,300,000	$ 24,600,000	$ 24,500,000
Total capitalized interest cost on unproved properties				7,700,000	7,400,000	6,100,000
Estimated useful lives of the property, minimum				2
Estimated useful lives of the property, maximum				20
Discount rate for estimated future net revenues from proved properties		10.00%
Non cash write-down of oil and gas properties			79,300,000
Material natural gas imbalances				0	0
Allowance for doubtful accounts receivable, current		100,000		100,000	100,000
Accounts receivable related to oil and gas sales		54,700,000		54,700,000	43,300,000
Accounts receivable		64,392,000		64,392,000	46,975,000
Net gain (loss) related to derivative activities, recognized				(900,000)	700,000	(1,400,000)
Fair value of derivative instruments		100,000		100,000	300,000
Other receivables related to natural gas hedges					less than 0.1
Inventory Obsolescence Charge				2,100,000
Decrease in retained earnings for uncertain tax positions	1,000,000
Percentage of working interest interest in wells				100.00%
Total amount of supervision fees charged to wells				12,900,000	12,500,000	11,400,000
Inventories carried at cost		3,600,000		3,600,000	12,800,000
Outstanding checks included in trade accounts payable		18,700,000		18,700,000	8,100,000
Maturity time period for cash and cash equivalents				3 months or less
Percentage of oil and gas sales to shell oil company				49.00%	52.00%	48.00%
Restricted cash and cash equivalents included in other long term assets		1,300,000		1,300,000	1,300,000
Accumulated other comprehensive income (loss) net of tax		0		0
Total comprehensive income (loss)				98,959,000	46,379,000	(39,553,000)
Asset retirement obligation classified as a current liability in accounts payable and accrued liabilities		9,279,000		9,279,000	8,708,000
Public stock offer price per share					$ 36.60	$ 18.50
Public stock offering (shares)					4,038,270	6,210,000
Proceeds from Issuance of Common Stock					147,800,000	114,900,000
Payments of stock issuance costs including commissions					7,700,000	6,100,000
January production covered by oil floor		81,500		81,500
Strike price of one oil price floor		96.80		96.80
Percentage of Oil and gas gross receipts from Flint Hills Resources				14.00%
Maximum percentage of gross receipts from other purchasers				10.00%
Proceeds from sale of asset retirement obligation				27,700,000
South Louisiana [Member]
Sale of Interest (Textual) [Abstract]
Number of field in which interest sold				6
Texas [Member]
Sale of Interest (Textual) [Abstract]
Number of field in which interest sold				2
Alabama [Member]
Sale of Interest (Textual) [Abstract]
Number of field in which interest sold				1
Senior Notes Due 2017 [Member]
Debt Issuance Costs (Textual) [Abstract]
Senior notes, issued		250,000,000		250,000,000
Senior notes stated percentage		7.125%		7.125%
Percentage at which senior notes are issued net of discount		100.00%		100.00%
Maturity date of senior notes				Jun. 01, 2017
Balance of issuance costs for credit facility		2,600,000		2,600,000
Net of accumulated amortization		1,500,000		1,500,000
Senior Notes Due 2020 [Member]
Debt Issuance Costs (Textual) [Abstract]
Senior notes, issued		225,000,000		225,000,000
Senior notes stated percentage		8.875%		8.875%
Percentage at which senior notes are issued net of discount		98.389%		98.389%
Effective yield to maturity				9.125%
Maturity date of senior notes				Jan. 15, 2020
Balance of issuance costs for credit facility		4,300,000		4,300,000
Net of accumulated amortization		700,000		700,000
Senior Notes Due 2022 [Member]
Debt Issuance Costs (Textual) [Abstract]
Senior notes, issued		250,000,000		250,000,000
Senior notes stated percentage		7.875%		7.875%
Percentage at which senior notes are issued net of discount		99.156%		99.156%
Effective yield to maturity				8.00%
Maturity date of senior notes				Mar. 01, 2022
Balance of issuance costs for credit facility		4,700,000		4,700,000
Net of accumulated amortization		100,000		100,000
Line of Credit [Member]
Debt Issuance Costs (Textual) [Abstract]
Balance of issuance costs for credit facility		3,500,000		3,500,000
Net of accumulated amortization		4,000,000		4,000,000
Joint Interest Owners [Member]
Accounts, Notes, Loans and Financing Receivable (Textual) [Abstract]
Accounts receivable related to joint interest owners		4,200,000		4,200,000	2,300,000
Other Receivables [Member]
Accounts, Notes, Loans and Financing Receivable (Textual) [Abstract]
Other Receivables		$ 5,600,000		$ 5,600,000	$ 1,400,000