Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Current assets: Derivative instruments	$ 4,378	$ 8,989
Other assets: Derivative instruments	771	847
Current liabilities: Derivative instruments	(670)	(171)
Long-term liabilities: Derivative instruments		(383)
Total Fair Value	4,479	9,282
Oil [Member] | Current Assets [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Current assets: Derivative instruments	3,064
Oil [Member] | Other assets [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Other assets: Derivative instruments	725
Oil [Member] | Current liabilities [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Current liabilities: Derivative instruments	(670)	(171)
Oil [Member] | Long-term liabilities [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Long-term liabilities: Derivative instruments		(383)
Natural Gas [Member] | Current Assets [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Current assets: Derivative instruments	1,089	8,989
Natural Gas [Member] | Other assets [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Other assets: Derivative instruments	46	847
NGL's [Member] | Current Assets [Member]
Summary of location and aggregate fair value of all derivative financial instruments recorded in the consolidated balance sheets
Current assets: Derivative instruments	$ 225