Divestiture and Merger Narrative (Details) - USD ($) $ in Thousands			3 Months Ended		9 Months Ended		18 Months Ended
	May 01, 2019	Mar. 19, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019
Business Acquisition [Line Items]
Relief of liabilities associated with properties					$ (7,668)
Loss on sale of properties			$ 0	$ 74	2,901	$ 1,046
Merger transaction expense			2,078	100	4,492	6,140
Fifth Creek
Business Acquisition [Line Items]
Business acquisition, equity interest issued or issuable, number of shares		100,000,000
Fair value of common stock issued		$ 484,000
Repayment of Fifth Creek debt		$ 53,900
Business combination, pro forma information, revenue of acquiree since acquisition date, actual				20,900		35,200
Business combination, pro forma information, expenses of acquiree since acquisition date, actual				13,700		25,100
Merger transaction expense							$ 21,200
Acquisition-related Costs
Business Acquisition [Line Items]
Merger transaction expense			$ 2,100	$ 100	4,500	6,100
Fifth Creek | Acquisition-related Costs
Business Acquisition [Line Items]
Merger transaction expense					$ 0	$ 4,000
DJ Basin
Business Acquisition [Line Items]
Relief of liabilities associated with properties	$ (7,700)
Loss on sale of properties	$ 2,300