Commitments and Contingencies Commitments and Contingencies (Details)	1 Months Ended	3 Months Ended		9 Months Ended
	May 31, 2016 USD ($)	Sep. 30, 2016 USD ($) Tcf Bcf MMBbls	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) $ / MMBTU Tcf Bcf MMBbls	Sep. 30, 2015 USD ($)
Other Commitments [Line Items]
Additional expense due to unutilized firm transportation and shortfalls in delivering or transporting minimum volumes under certain commitments		$ 12,000,000	$ 6,000,000	$ 39,000,000	$ 15,000,000
Supplemental environmental projects	$ 178,780
Reduced penalty	$ 44,695
CONSOL Carried Cost Obligation [Member]
Other Commitments [Line Items]
Equity method investment, ownership percentage		50.00%		50.00%
Maximum amount to be paid each calendar year for funding of future drilling and completion costs				$ 400,000,000
Funding of joint venture's future drilling and completion costs				$ 1,600,000,000
Natural gas price agreed upon benchmark, average				4.00
Consent Decree [Member]
Other Commitments [Line Items]
Civil penalty				$ 4,950,000
Mitigation projects				4,500,000
Supplemental environmental projects				$ 4,000,000
Natural Gas [Member]
Other Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Available Amounts to be Received | Tcf		6		6
Crude Oil [Member]
Other Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Available Amounts to be Received | MMBbls		271		271
Marcellus Shale [Member] | Natural Gas [Member]
Other Commitments [Line Items]
Oil and Gas Delivery Commitments and Contracts, Available Amounts to be Received | Bcf		493		493