Derivative Financial Instruments (Details 2) (USD $) In Thousands, unless otherwise specified	Sep. 30, 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	$ 6,395	$ 8,989
Current liabilities: Derivative instruments		171
Other assets: Derivative instruments	1,880	847
Long-term liabilities: Derivative instruments	142	383
Total Fair Value	8,133	9,282
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		(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)
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	3,736
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	1,880
Natural Gas [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	(138)
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	2,610	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		847
NGL's [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	(4)
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	$ 49