Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized (loss) gain on derivatives	$ (1,165)	$ 3,371	$ (519)	$ 11,147
Unrealized gain (loss) on derivatives	(9,327)	(12,993)	(6,626)	(1,149)
Total	(10,492)	(9,622)	(7,145)	9,998
Revenues [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized (loss) gain on derivatives	(1,165)	3,371	(519)	11,147
Unrealized gain (loss) on derivatives	(9,327)	(12,993)	(6,626)	(1,149)
Oil [Member] | Revenues [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized (loss) gain on derivatives	(1,519)	374	(1,984)	1,093
Unrealized gain (loss) on derivatives	(8,132)	(9,053)	(6,818)	(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 (loss) gain on derivatives	161	2,996	790	10,053
Unrealized gain (loss) on derivatives	57	(3,985)	(132)	6,170
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 (loss) gain on derivatives	193	1	675	1
Unrealized gain (loss) on derivatives	$ (1,252)	$ 45	$ 324	$ 45