Derivative Financial Instruments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 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	$ 254	$ 4,713	$ 646	$ 7,776
Unrealized gain (loss) on derivatives	7,526	15,114	2,701	11,844
Total	7,780	19,827	3,347	19,620
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	254	4,713	646	7,776
Unrealized gain (loss) on derivatives	7,526	15,114	2,701	11,844
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	(228)	719	(465)	719
Unrealized gain (loss) on derivatives	4,042	20,483	1,314	15,223
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	105	3,994	629	7,057
Unrealized gain (loss) on derivatives	2,323	(5,369)	(189)	(3,379)
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	377	0	482	0
Unrealized gain (loss) on derivatives	$ 1,161	$ 0	$ 1,576	$ 0