Summary of Significant Accounting Policies (Details Textual) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	May 01, 2013	Dec. 31, 2012
Accounts Receivable (Textual) [Abstract]
Allowance for doubtful accounts receivable, current	$ 100,000		$ 100,000			$ 100,000
Summary of Significant Accounting Policies (Textual) [Abstract]
Total capitalized internal costs	7,500,000	7,800,000	16,000,000	16,200,000
Total capitalized interest cost on unproved properties	1,900,000	2,000,000	3,800,000	4,000,000
Discount rate for estimated future net revenues from proved properties			10.00%
Net gain (loss) on derivative activities	1,500,000	2,600,000	1,200,000	2,300,000
Unrealized Gain (Loss) on Derivatives	1,800,000		1,800,000
Fair value of derivative instruments	2,100,000		2,100,000
Receivables from settled derivatives	200,000		200,000
Percentage of working interest in wells			100.00%
Total amount of supervision fees charged to wells	3,300,000	2,900,000	6,100,000	5,800,000
Inventories carried at cost	2,800,000		2,800,000			5,600,000
Outstanding checks included in trade accounts payable	27,900,000		27,900,000			13,300,000
Maturity Period of Cash and cash Equivalents			3 months
Restricted cash and cash equivalents included in other long term assets	1,000,000		1,000,000			1,000,000
Reduction of asset retirement obligation due to sale of properties					11,300,000
Asset Retirement Obligation - current portion	9,520,000		9,520,000			7,134,000
Senior Notes Due Two Thousand Seven Teen [Member]
Debt Issuance Costs (Textual) [Abstract]
Balance of issuance costs for credit facility	2,000,000		2,000,000
Debt Instrument, Interest Rate, Stated Percentage	7.125%		7.125%
Senior Notes Due Two Thousand Twenty [Member]
Debt Issuance Costs (Textual) [Abstract]
Balance of issuance costs for credit facility	3,800,000		3,800,000
Debt Instrument, Interest Rate, Stated Percentage	8.875%		8.875%
Senior Notes Due 2022 [Member]
Debt Issuance Costs (Textual) [Abstract]
Balance of issuance costs for credit facility	6,800,000		6,800,000
Debt Instrument, Interest Rate, Stated Percentage	7.875%		7.875%
Line of Credit [Member]
Debt Issuance Costs (Textual) [Abstract]
Balance of issuance costs for credit facility	3,800,000		3,800,000
Trade Accounts Receivable [Member]
Accounts Receivable (Textual) [Abstract]
Trade Accounts Receivable, Gross	48,000,000		48,000,000			53,900,000
Joint Interest Owners [Member]
Accounts Receivable (Textual) [Abstract]
Accounts receivable related to joint interest owners	2,600,000		2,600,000			3,600,000
Other Accounts Receivable [Member]
Accounts Receivable (Textual) [Abstract]
Other Receivables	14,000,000		14,000,000			9,800,000
Maximum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life			20 years
Minimum [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Property, Plant and Equipment, Useful Life			2 years
Natural Gas [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Fair value of derivative instruments	$ 2,100,000		$ 2,100,000
Natural Gas [Member] | Derivative, Floor [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Future Gas Production Hedged in MMBTU (Energy Item Type)	1,240,000		1,240,000
Derivative, Floor Strike Price	3.95		3.95
Natural Gas [Member] | Derivative, Collar [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Future Gas Production Hedged in MMBTU (Energy Item Type)	3,010,000		3,010,000
Derivative, Floor Strike Price	3.75		3.75
Derivative, Call Strike Price	5.05		5.05
Natural Gas [Member] | Derivative, Participating Collar [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Future Gas Production Hedged in MMBTU (Energy Item Type)	1,800,000		1,800,000
Derivative, Floor Strike Price	4.00		4.00
Derivative, Call Strike Price	5.00		5.00
Derivative, particpating collar (cap price)	6.00		6.00
Oil [Member] | Derivative, Participating Collar [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Future Production Hedged (Oil)	201,000		201,000
Derivative, Floor Strike Price	90.00		90.00
Derivative, Call Strike Price	100.00		100.00
Derivative, particpating collar (cap price)	108.00		108.00