Concentrations (Details Textual) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Additional Concentrations (Textual) [Abstract]
Maximum amount of credit risk exposure	$ 69,914
Production associated with Gulf Coast Basin properties	97.00%
Estimated proved reserves derived from Gulf Coast Basin Reservoirs	50.00%
Estimated reserves derived from reservoirs associated with deep water and deep shelf gas properties	21.00%
Additional amount in accounts of J.P. Morgan Chase and Co.	29,868
J.P. Morgan Prime Money Market Fund [Member]
Concentrations (Textual) [Abstract]
Investment in J.P. Morgan Prime Money Market Fund	$ 5,551
Hess Corporation [Member]
Concentrations (Textual) [Abstract]
Revenue derived from Customers, Maximum Percentage	10.00%
Sequent Energy Management LP [Member]
Concentrations (Textual) [Abstract]
Revenue derived from Customers, Maximum Percentage	10.00%