Derivative Instruments and Hedging Activities (Details) (USD $)	3 Months Ended				9 Months Ended																6 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013		Apr. 01, 2014	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of Jul. 2014 - Dec. 2014 MMcf	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of Jul. 2014 - Dec. 2014 Minimum	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of Jul. 2014 - Dec. 2014 Maximum	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of Jul. 2014 - Dec. 2014 Weighted Average	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Swaps with contract period of Jul. 2014 - Dec. 2014 Weighted Average MMcf	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of January 2015 to December 2015 MMcf	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of January 2015 to December 2015 Minimum	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of January 2015 to December 2015 Maximum	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Collars with contract period of January 2015 to December 2015 Weighted Average	Sep. 30, 2014 Derivatives Designated as Hedges Natural Gas Swaps with contract period of January 2015 to December 2015 Weighted Average MMcf	Sep. 30, 2014 Derivatives Designated as Hedges Crude Oil Swaps with contract period of Jul. 2014 - Dec. 2014 Weighted Average MBbls	Sep. 30, 2014 Natural Gas and Oil Revenue [Member]
Derivative disclosures
Unrealized losses included in accumulated other comprehensive income and will reclassified into natural gas and crude oil revenues , pre-tax									$ 73,400,000
Unrealized losses included in accumulated other comprehensive income and will reclassified into natural gas and crude oil revenues , net of tax									44,200,000
Reclassification adjustment for settled cash flow hedge contracts(1)	12,965,000	[1]	(11,942,000)	[1]	69,337,000	[1]	(22,372,000)	[1]													26,800,000	[2]
Cash Flow Hedge Gain (Loss) to be Reclassified Remainder of Year					$ (17,400,000)
Volume										84,900.0				26,800.0	35,500.0				35,500.0	184.0
Collar Floor Price											3.60	4.37	4.13					3.86
Collar Ceiling Price											4.22	4.80	4.51			4.36	4.43	4.40
Swaps Weighted Average														4.05					4.12	97.00

[1] Net of income taxes of $(8,592) and $7,742 for the three months ended September 30, 2014 and 2013, respectively, and $(45,951) and $14,504 for the nine months ended September 30, 2014 and 2013, respectively.

[2] The Company ceased hedge accounting effective April 1, 2014. For the three and nine months ended September 30, 2014, a loss of approximately $21.6 million and $44.5 million, respectively, were reclassified into income. These amounts were previously frozen in accumulated other comprehensive income (loss).