Derivative Instruments and Hedging Activities (Details) (USD $)	Sep. 30, 2011 MMBtu
Natural Gas Costless Collars One [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	90,000
Purchased Put Nymex	$ 5.75
Written Call Nymex	7.65
Natural Gas Costless Collars Two [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	120,000
Purchased Put Nymex	5.75
Written Call Nymex	7.40
Natural Gas Costless Collars Three [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	120,000
Purchased Put Nymex	5.00
Written Call Nymex	6.55
Oil Costless Collars One [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	152,500
Purchased Put Nymex	65.00
Written Call Nymex	97.20
Oil Costless Collars Two [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	152,500
Purchased Put Nymex	65.00
Written Call Nymex	98.55
Oil Costless Collars Three [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	152,500
Purchased Put Nymex	65.00
Written Call Nymex	100.40
Oil Costless Collars Four [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	152,500
Purchased Put Nymex	65.00
Written Call Nymex	100.00
Oil Costless Collars Five [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	21,000
Purchased Put Nymex	65.00
Written Call Nymex	88.25
Oil Costless Collars Six [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	15,000
Purchased Put Nymex	60.00
Written Call Nymex	97.25
Oil Costless Collars Seven [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	15,000
Purchased Put Nymex	65.00
Written Call Nymex	108.00
Oil Costless Collars Eight [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	12,000
Purchased Put Nymex	70.00
Written Call Nymex	106.80
Oil Costless Collars Nine [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	12,000
Purchased Put Nymex	75.00
Written Call Nymex	102.60
Oil Costless Collars Ten [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	9,000
Purchased Put Nymex	65.00
Written Call Nymex	100.00
Oil Costless Collars Eleven [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	9,000
Purchased Put Nymex	75.00
Written Call Nymex	104.30
Oil Costless Collars Twelve [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	46,000
Purchased Put Nymex	65.00
Written Call Nymex	100.00
Oil Costless Collars Thirteen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	46,000
Purchased Put Nymex	65.00
Written Call Nymex	100.00
Oil Costless Collars Fourteen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	46,000
Purchased Put Nymex	65.00
Written Call Nymex	106.50
Oil Costless Collars Fifteen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	6,000
Purchased Put Nymex	75.00
Written Call Nymex	103.00
Oil Costless Collars Sixteen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	6,000
Purchased Put Nymex	75.00
Written Call Nymex	95.15
Oil Costless Collars Seventeen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	46,000
Purchased Put Nymex	65.00
Written Call Nymex	99.00
Oil Costless Collars Eighteen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	46,000
Purchased Put Nymex	65.00
Written Call Nymex	97.40
Oil Costless Collars Nineteen [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	184,000
Purchased Put Nymex	90.00
Written Call Nymex	144.00
Oil Costless Collars Twenty [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	6,000
Purchased Put Nymex	70.00
Written Call Nymex	96.35
Oil Costless Collars Twenty One [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	60,000
Purchased Put Nymex	75.00
Written Call Nymex	106.90
Oil Costless Collars Twenty Two [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	182,000
Purchased Put Nymex	65.00
Written Call Nymex	100.75
Oil Costless Collars Twenty Three [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	91,000
Purchased Put Nymex	65.00
Written Call Nymex	101.00
Oil Costless Collars Twenty Four [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	182,000
Purchased Put Nymex	65.00
Written Call Nymex	99.25
Oil Costless Collars Twenty Five [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	91,000
Purchased Put Nymex	65.00
Written Call Nymex	102.75
Oil Costless Collars Twenty Six [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	136,500
Purchased Put Nymex	65.00
Written Call Nymex	107.25
Oil Costless Collars Twenty Seven [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	106,500
Purchased Put Nymex	65.00
Written Call Nymex	110.00
Oil Costless Collars Twenty Eight [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	366,000
Purchased Put Nymex	85.00
Written Call Nymex	139.50
Oil Costless Collars Twenty Nine [Member]
Summary of open commodity derivative contracts
Inception Date	Feb. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	335,000
Purchased Put Nymex	80.00
Written Call Nymex	134.25
Oil Costless Collars Thirty[ Member]
Summary of open commodity derivative contracts
Inception Date	Jul. 01, 2012
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	62,000
Purchased Put Nymex	65.00
Written Call Nymex	102.25
Oil Costless Collars Thirty One [Member]
Summary of open commodity derivative contracts
Inception Date	Apr. 01, 2012
Maturity Date	Apr. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	15,000
Purchased Put Nymex	80.00
Written Call Nymex	102.50
Oil Costless Collars Thirty Two [Member]
Summary of open commodity derivative contracts
Inception Date	Jun. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	25,000
Purchased Put Nymex	80.00
Written Call Nymex	102.50
Oil Costless Collars Thirty Three [Member]
Summary of open commodity derivative contracts
Inception Date	Jul. 01, 2012
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	31,000
Purchased Put Nymex	65.00
Written Call Nymex	105.25
Oil Costless Collars Thirty Four [Member]
Summary of open commodity derivative contracts
Inception Date	Jul. 01, 2012
Maturity Date	Jul. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	62,000
Purchased Put Nymex	75.00
Written Call Nymex	114.00
Oil Costless Collars Thirty Five [Member]
Summary of open commodity derivative contracts
Inception Date	Jul. 01, 2012
Maturity Date	Sep. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	92,000
Purchased Put Nymex	65.00
Written Call Nymex	109.40
Oil Costless Collars Thirty Six [Member]
Summary of open commodity derivative contracts
Inception Date	Aug. 01, 2012
Maturity Date	Sep. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	61,000
Purchased Put Nymex	65.00
Written Call Nymex	110.25
Oil Costless Collars Thirty Seven [Member]
Summary of open commodity derivative contracts
Inception Date	Aug. 01, 2012
Maturity Date	Sep. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	61,000
Purchased Put Nymex	65.00
Written Call Nymex	112.00
Oil Costless Collars Thirty Eight [Member]
Summary of open commodity derivative contracts
Inception Date	Aug. 01, 2012
Maturity Date	Oct. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	92,000
Purchased Put Nymex	70.00
Written Call Nymex	110.90
Oil Costless Collars Thirty Nine [Member]
Summary of open commodity derivative contracts
Inception Date	Aug. 01, 2012
Maturity Date	Oct. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	92,000
Purchased Put Nymex	70.00
Written Call Nymex	106.50
Oil Costless Collars Forty [Member]
Summary of open commodity derivative contracts
Inception Date	Aug. 01, 2012
Maturity Date	Oct. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	276,000
Purchased Put Nymex	75.00
Written Call Nymex	112.50
Oil Costless Collars Forty One [Member]
Summary of open commodity derivative contracts
Inception Date	Sep. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	110,000
Purchased Put Nymex	80.00
Written Call Nymex	102.50
Oil Costless Collars Forty Two [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2012
Maturity Date	Oct. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	62,000
Purchased Put Nymex	65.00
Written Call Nymex	112.65
Oil Costless Collars Forty Three [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2012
Maturity Date	Oct. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	31,000
Purchased Put Nymex	70.00
Written Call Nymex	110.90
Oil Costless Collars Forty Four [Member]
Summary of open commodity derivative contracts
Inception Date	Nov. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	122,000
Purchased Put Nymex	70.00
Written Call Nymex	107.70
Oil Costless Collars Forty Five [Member]
Summary of open commodity derivative contracts
Inception Date	Nov. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	122,000
Purchased Put Nymex	70.00
Written Call Nymex	110.00
Oil Costless Collars Forty Six [Member]
Summary of open commodity derivative contracts
Inception Date	Nov. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	244,000
Purchased Put Nymex	75.00
Written Call Nymex	112.50
Oil Costless Collars Forty Eight [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2013
Maturity Date	Mar. 31, 2013
Natural Gas (MMBTU) & Crude Oil (Barrels)	180,000
Purchased Put Nymex	80.00
Written Call Nymex	120.00
Oil Costless Collars Forty Seven [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2013
Maturity Date	Feb. 28, 2013
Natural Gas (MMBTU) & Crude Oil (Barrels)	118,000
Purchased Put Nymex	75.00
Written Call Nymex	113.05
Oil Costless Collars Forty Nine [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2013
Maturity Date	Mar. 31, 2013
Natural Gas (MMBTU) & Crude Oil (Barrels)	270,000
Purchased Put Nymex	80.00
Written Call Nymex	129.45
Oil Costless Collars Fifty [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2013
Maturity Date	May 31, 2013
Natural Gas (MMBTU) & Crude Oil (Barrels)	302,000
Purchased Put Nymex	85.00
Written Call Nymex	134.00
Oil Costless Collars Fifty One [Member]
Summary of open commodity derivative contracts
Inception Date	Mar. 01, 2013
Maturity Date	Mar. 31, 2013
Natural Gas (MMBTU) & Crude Oil (Barrels)	62,000
Purchased Put Nymex	80.00
Written Call Nymex	120.00
Oil Costless Collars Fifty Two [Member]
Summary of open commodity derivative contracts
Inception Date	Apr. 01, 2013
Maturity Date	Sep. 30, 2013
Natural Gas (MMBTU) & Crude Oil (Barrels)	540,000
Purchased Put Nymex	75.00
Written Call Nymex	109.00
Crude Oil Calls One [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Dec. 31, 2011
Natural Gas (MMBTU) & Crude Oil (Barrels)	138,000
Written Call Nymex	100.00
Crude Oil Puts One [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	137,000
Purchased Put Nymex	65.00
Crude Oil Puts Two [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	137,000
Purchased Put Nymex	65.00
Crude Oil Puts Three [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	68,500
Purchased Put Nymex	65.00
Crude Oil Puts Four [Member]
Summary of open commodity derivative contracts
Inception Date	Oct. 01, 2011
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	68,500
Purchased Put Nymex	65.00
Crude Oil Puts Five [Member]
Summary of open commodity derivative contracts
Inception Date	Jul. 01, 2012
Maturity Date	Dec. 31, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	276,000
Purchased Put Nymex	80.00
Crude Oil Three Way Costless Collars One [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 01, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	136,500
Purchased Put Nymex	80.00
Written Call Nymex	107.50
Written Put Nymex	65.00
Crude Oil Three Way Costless Collars Two [Member]
Summary of open commodity derivative contracts
Inception Date	Jan. 02, 2012
Maturity Date	Jun. 30, 2012
Natural Gas (MMBTU) & Crude Oil (Barrels)	136,500
Purchased Put Nymex	80.00
Written Call Nymex	107.50
Written Put Nymex	$ 65.00