Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated statements of operations
Realized gain on derivatives	$ 392	$ 3,063
Unrealized loss on derivatives	(4,825)	(3,270)
Total	(4,433)	(207)
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	392	3,063
Unrealized loss on derivatives	(4,825)	(3,270)
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	(237)
Unrealized loss on derivatives	(2,728)	(5,260)
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	524	3,063
Unrealized loss on derivatives	(2,511)	1,990
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	105
Unrealized loss on derivatives	$ 414