Derivative Financial Instruments (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized gain on derivatives	$ 3,371	$ 1,435	$ 11,147	$ 4,237
Unrealized (loss) gain on derivatives	(12,993)	2,870	(1,149)	1,534
Total	(9,622)	4,305	9,998	5,771
Revenues [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized gain on derivatives	3,371	1,435	11,147	4,237
Unrealized (loss) gain on derivatives	(12,993)	2,870	(1,149)	1,534
Oil [Member] | Revenues [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized gain on derivatives	374		1,093
Unrealized (loss) gain on derivatives	(9,053)		(7,364)
Natural Gas [Member] | Revenues [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized gain on derivatives	2,996	1,435	10,053	4,237
Unrealized (loss) gain on derivatives	(3,985)	2,870	6,170	1,534
NGL's [Member] | Revenues [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized gain on derivatives	1		1
Unrealized (loss) gain on derivatives	$ 45		$ 45