Mergers, Acquisitions, Exchanges and Divestitures - Summary (Details) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Mar. 19, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Asset Retirement Obligations Disposition Of Properties		$ 7,668	$ 351	$ 5,138
Business Acquisition, Pro Forma Revenue		452,659	468,949	291,991
Asset retirement obligations	$ 7,400			8,700
Accumulated amortization of right-of-use asset		1,142
Gain (Loss) on Disposition of Oil and Gas Property		(2,901)	(1,046)	92
Merger transaction expense		4,492	7,991	8,749
Business Acquisition, Pro Forma Net Income (Loss)		$ (131,407)	$ 125,281	$ (143,530)
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax, Per Share, Basic		$ (0.62)	$ 0.60	$ (0.81)
Business Acquisition, Pro Forma Income (Loss) from Continuing Operations, Net of Tax, Per Share, Diluted		$ (0.62)	$ 0.60	$ (0.81)
Uinta Basin
Proceeds from Divestiture of Businesses			$ 101,300
Non-cash impairment of oil and gas properties				$ 37,900
Proved properties				409,957
Unproved oil and gas properties, excluded from amortization				397
Furniture, equipment and other				1,593
Accumulated depreciation, depletion, amortization and impairment				(304,939)
Total assets				107,008
Asset retirement obligation				4,773
Total liabilities				4,773
Net assets				102,235
Gain (Loss) on Disposition of Proved Property			(1,000)
DJ Basin, Non-Core
Asset Retirement Obligations Disposition Of Properties		$ 7,700
Gain (Loss) on Disposition of Oil and Gas Property		$ (2,300)
Proved Oil And Gas Properties
Acquisition Costs, Period Cost				9,100
Unproved Oil And Gas Properties
Acquisition Costs, Period Cost				11,200
Level 3
Acquisition Costs, Period Cost				11,600
Fifth Creek
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual			59,400
Business Combination, Pro Forma Information, Expenses of Acquiree since Acquisition Date, Actual			44,200
Fair value of common stock issued	484,000
Plus: Repayment of Fifth Creek debt	53,900
Total purchase price	537,900
Accounts payable and accrued liabilities	25,782
Current unfavorable contract	2,651
Other current liabilities	13,797
Asset retirement obligations	7,361
Long-term deferred tax liability	137,707
Long-term unfavorable contract	4,449
Other noncurrent liabilities	2,354
Total purchase price plus liabilities assumed	732,001
Cash	543
Accounts receivable	7,831
Proved oil and gas properties	105,702
Unproved oil and gas properties	609,568
Asset retirement obligations	7,361
Furniture, equipment and other	931
Other noncurrent assets	65
Total asset value	$ 732,001
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares	100,000,000
Acquisition-related Costs | Fifth Creek
Merger transaction expense			$ 4,000	$ 2,200