Ceiling Test (Details) (USD $)	3 Months Ended
	Mar. 31, 2013 Rate	Mar. 31, 2012
Ceiling Test (Textual) [Abstract]
Increase (Decrease) in ceiling test write-downs	$ 0	$ 20,111,000
Cash Flow Hedge, Decrease in Impairment of Gas and Oil Properties		$ 1,200,000
Ceiling Test (Additional Textual) [Abstract]
Rate for discounting future cash flows	10.00%
Mcf of natural gas [Member]
Ceiling Test (Textual) [Abstract]
Average sales prices		2.97
Barrel of oil [Member]
Ceiling Test (Textual) [Abstract]
Average sales prices		107.99
Mcfe of Ngl [Member]
Ceiling Test (Textual) [Abstract]
Average sales prices		8.74