Commitments and Contingencies Commitments and Contingencies (Details) (USD $)	1 Months Ended	9 Months Ended
	Feb. 28, 2014 MMBTU	Sep. 30, 2014
Other Commitments [Line Items]
Equity Method Investment, Ownership Percentage		32.10%
CONSOL Carried Cost Obligation [Member]
Other Commitments [Line Items]
Maximum amount to be paid each calendar year for funding of future drilling and completion costs		$ 400,000,000
Equity Method Investment, Ownership Percentage		50.00%
Funding of joint venture's future drilling and completion costs		2,100,000,000
Natural gas price agreed upon benchmark, average		4.00
Forecast On Venture To Explore and Develop Oil and Gas Properties		185,000,000
Marcellus Shale Firm Transportation Agreement [Member]
Other Commitments [Line Items]
Long-term Purchase Commitment, Minimum Volume Required Per Day	445,000
Long-term Purchase Commitment, Amount		$ 1,200,000,000
Long-term Purchase Commitment, Time Period	15 years