Acquisitions (Details)					1 Months Ended		12 Months Ended
	Aug. 31, 2015 USD ($)	Jun. 29, 2015 USD ($) a	Jun. 12, 2015 USD ($) a well mi Mcf	Jun. 09, 2015 USD ($) a	Dec. 31, 2015 USD ($)	Apr. 30, 2015 USD ($) a	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Business Acquisition [Line Items]
Deductions to cash held in escrow							$ (185,000,000)	$ 0	$ 0
Paloma Partners III, LLC
Business Acquisition [Line Items]
Purchase price	$ 302,300,000					$ 301,900,000
Net nonproducing oil and gas acreage (in acres) | a						24,000
Amount put in escrow	$ 30,100,000					$ 75,000,000
American Energy - Utica, LLC
Business Acquisition [Line Items]
Purchase price		$ 405,400,000
Amount put in escrow			$ 67,100,000
Cash, net of purchase price adjustments		405,000,000	405,029,000
Deductions to cash held in escrow					$ 2,400,000
Goodwill			0
Bargain purchase gain			0
Belmont And Jefferson Counties, Ohio | American Energy - Utica, LLC
Business Acquisition [Line Items]
Purchase price				$ 68,200,000
Gross and net acquired oil and gas acreage (in acres) | a				6,198
Monroe County, Ohio | American Energy - Utica, LLC
Business Acquisition [Line Items]
Purchase price		$ 18,200,000	$ 319,000,000
Net nonproducing oil and gas acreage (in acres) | a		1,900	27,228
Gross oil and gas acreage acquired (in acres) | a		4,950	38,965
Net average per day production volume (MMcf) | Mcf			14,600
Gross number of wells acquired | well			18
Net number of wells acquired | well			11.3
Length of gas gathering transportation | mi			11
Number of well pad locations | well			4