Acquisitions and Divestitures - Narrative (Details) - USD ($) $ in Thousands			8 Months Ended	12 Months Ended
	Oct. 05, 2018	Dec. 20, 2017	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	May 09, 2017
Business Acquisition [Line Items]
Total cash consideration				$ 5,965	$ 34,735
Gain on sale of oil and gas properties, net				1,919	9,105
Non-core Properties
Business Acquisition [Line Items]
Total cash consideration				6,000	7,500
Total cash consideration for eliminating of future abandonment obligations				800	4,000
Gain on sale of oil and gas properties, net				4,700	$ 6,100
Williston Basin
Business Acquisition [Line Items]
Total cash consideration		$ 26,400
Gain on sale of oil and gas properties, net		3,000
Normal and customary purchase price adjustments to account for net cash flows		$ 900
Bold Transaction
Business Acquisition [Line Items]
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets						$ 570,137
Revenues			$ 50,200
Direct operating expenses			$ 23,800
Acreage Trade | Midland Basin
Business Acquisition [Line Items]
Cash payments for oil and gas properties	$ 25,900
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Assets	37,100
Oil and gas properties acquired	65,800
Accounts payable acquired	$ 2,800
Gain on sale of oil and gas properties, net				2,800
Oil and gas properties relieved				$ 39,900