Commitments and Contingencies (Details) - USD ($) $ in Thousands			1 Months Ended	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2017	Feb. 17, 2017	May 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2015
Commitments and Contingencies (Textual) [Abstract]
Natural gas processing and transportation agreement						5 years
Minimum delivery commitment to avoid paying gas deficiency fee						80.00%
Transportation and processing fee under the agreement				$ 400	$ 700	$ 1,400	$ 2,400
Drilling Rig Commitments
Commitments and Contingencies (Textual) [Abstract]
Maximum termination outstanding obligations of contracts				36,117		36,117
Outside Operated Drilling Commitments
Commitments and Contingencies (Textual) [Abstract]
Maximum termination outstanding obligations of contracts				28,500		28,500
Eagle Ford Acreage Agreement [Member]
Commitments and Contingencies (Textual) [Abstract]
Future undiscounted minimum payments, minimum				0		0
Loving County System Agreement
Commitments and Contingencies (Textual) [Abstract]
Transportation and processing fee under the agreement				4,000	$ 2,400	10,800	$ 7,100
Agreement term								15 years
Deficiency fee required to be paid						11,400
Capital Addition Purchase Commitments [Member]
Commitments and Contingencies (Textual) [Abstract]
Remaining commitments	$ 24,700		$ 57,000
Payment for long-term purchase commitment				22,400		32,300
Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Commitments and Contingencies (Textual) [Abstract]
Contractual obligation				$ 245,600		$ 245,600
Rustler Breaks and Wolf Asset Area [Member] | Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Commitments and Contingencies (Textual) [Abstract]
Term of contractual obligation		15 years
Rustler Breaks Asset Area [Member] | Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Commitments and Contingencies (Textual) [Abstract]
Term of contractual obligation		15 years