Business Combinations and Divestitures (Details) $ in Millions				11 Months Ended	12 Months Ended
	Feb. 17, 2017 USD ($) well	Oct. 01, 2015 USD ($)	Feb. 27, 2015 USD ($) a shares	Jan. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2017	Oct. 31, 2015 USD ($)
Business Acquisition [Line Items]
Subsidiary ownership percentage					100.00%
Carrying value of net assets sold							$ 31.0
Sale leaseback transaction, transaction costs					$ 0.4
Sale leaseback transaction, current period gain recognized					107.3
Harvey E Yates Company [Member]
Business Acquisition [Line Items]
Number of gross acres in acreage acquired | a			58,600
Number of net acres in acreage acquired | a			18,200
Business combination, consideration transferred, liabilities incurred			$ 33.6
Shares issued upon conversion | shares			10
Harvey E Yates Company [Member] | Common Stock [Member]
Business Acquisition [Line Items]
Shares issued for acquisition | shares			3,300,000
Harvey E Yates Company [Member] | Convertible Preferred Stock [Member]
Business Acquisition [Line Items]
Shares issued for acquisition | shares			150,000
EnLink [Member]
Business Acquisition [Line Items]
Proceeds from sale of oil and gas property and equipment		$ 143.4
Proceeds from sale of oil and gas property and equipment net of purchase price adjustments		139.8
Purchase price adjustments for production, revenues and operating and capital expenditures		$ 3.6
Gas gathering and processing agreement, term		15 years
Sale leaseback transaction, deferred gain					$ 108.4
Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Business Acquisition [Line Items]
Subsidiary ownership percentage	51.00%					51.00%
Deferred performance incentives	$ 58.8
Deferred performance incentives, term	4 years
Contributions to joint venture, operating capital	$ 5.1
Corporate Joint Venture [Member] | San Mateo Midstream [Member] | Subsequent Event [Member]
Business Acquisition [Line Items]
Deferred performance incentives				$ 14.7
Five Point [Member] | Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Business Acquisition [Line Items]
Subsidiary ownership percentage	49.00%
Payments to acquire interest in joint venture	$ 176.4
Proceeds from divestiture of interest in joint venture	$ 171.5
Rustler Breaks and Wolf Asset Area [Member] | Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Business Acquisition [Line Items]
Contractual obligation, term	15 years
Rustler Breaks Asset Area [Member] | Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Business Acquisition [Line Items]
Number of wells contributed to joint venture | well	1
Contractual obligation, term	15 years
Wolf Asset Area [Member] | Corporate Joint Venture [Member] | San Mateo Midstream [Member]
Business Acquisition [Line Items]
Number of wells contributed to joint venture | well	3