Ceiling Test (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 Rate	Sep. 30, 2011	Sep. 30, 2012 Mcf of natural gas [Member]	Sep. 30, 2012 Barrel of oil [Member]	Sep. 30, 2012 Mcfe of Ngl [Member]
Ceiling Test (Textual) [Abstract]
Average sales prices					2.22	104.83	7.44
Increase (Decrease) in ceiling test write-downs	$ 35,391,000	$ 0	$ 108,987,000	$ 18,907,000
Cash Flow Hedge, Decrease in Impairment of Gas and Oil Properties			$ (2,100,000)
Ceiling Test (Additional Textual) [Abstract]
Rate for discounting future cash flows			10.00%