Parent and Subsidiary Guarantor - Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	$ 278,635	$ 231,441	$ 121,990
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	(426,416)	(453,616)	(239,631)
Additions to furniture, fixtures and other	(4,662)	(853)	(926)
Repayment of debt associated with merger, net of cash acquired	0	(53,357)	0
Proceeds from sale of properties	1,334	(221)	101,845
Other investing activities	(1,612)	364	(299)
Intercompany transfers	0		0
Cash flows from financing activities:
Proceeds from debt	222,000		275,000
Principal and redemption premium payments on debt	83,859	469	322,343
Proceeds from sale of common stock, net of offering costs	(1)	(1)	(110,710)
Intercompany transfers	0		0
Other financing activities	(1,746)	(4,982)	(7,721)
Increase (Decrease) in Cash and Cash Equivalents	(16,325)	(281,692)	38,625
Beginning Cash and Cash Equivalents	32,774	314,466	275,841
Ending Cash and Cash Equivalents	16,449	32,774	314,466
Reportable Legal Entities | Parent Issuer
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities			121,480
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions			(239,631)
Additions to furniture, fixtures and other			(926)
Proceeds from sale of properties			99,315
Other investing activities			(299)
Intercompany transfers			3,040
Cash flows from financing activities:
Proceeds from debt			275,000
Principal and redemption premium payments on debt			322,343
Proceeds from sale of common stock, net of offering costs			(110,710)
Intercompany transfers			0
Other financing activities			(7,721)
Increase (Decrease) in Cash and Cash Equivalents			38,625
Beginning Cash and Cash Equivalents		314,466	275,841
Ending Cash and Cash Equivalents			314,466
Reportable Legal Entities | Parent Guarantor
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	0	0
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	0	0
Additions to furniture, fixtures and other	0	0
Repayment of debt associated with merger, net of cash acquired		0
Proceeds from sale of properties	0	0
Other investing activities	0	0
Intercompany transfers	0
Cash flows from financing activities:
Proceeds from debt	0
Principal and redemption premium payments on debt	0	0
Proceeds from sale of common stock, net of offering costs	0	0
Intercompany transfers	0
Other financing activities	0	0
Increase (Decrease) in Cash and Cash Equivalents	0	0
Beginning Cash and Cash Equivalents	0	0
Ending Cash and Cash Equivalents	0	0	0
Reportable Legal Entities | Subsidiary Issuer
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	278,622	231,441
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	(426,416)	(453,616)
Additions to furniture, fixtures and other	(4,286)	(853)
Repayment of debt associated with merger, net of cash acquired		(53,357)
Proceeds from sale of properties	1,334	(221)
Other investing activities	(1,612)	364
Intercompany transfers	(363)
Cash flows from financing activities:
Proceeds from debt	222,000
Principal and redemption premium payments on debt	83,859	469
Proceeds from sale of common stock, net of offering costs	(1)	(1)
Intercompany transfers	0
Other financing activities	(1,746)	(4,982)
Increase (Decrease) in Cash and Cash Equivalents	(16,325)	(281,692)
Beginning Cash and Cash Equivalents	32,774	314,466
Ending Cash and Cash Equivalents	16,449	32,774	314,466
Reportable Legal Entities | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	13		510
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	0		0
Additions to furniture, fixtures and other	(376)		0
Proceeds from sale of properties	0		2,530
Other investing activities	0		0
Intercompany transfers	0		0
Cash flows from financing activities:
Proceeds from debt	0		0
Principal and redemption premium payments on debt	0		0
Proceeds from sale of common stock, net of offering costs	0		0
Intercompany transfers	363		(3,040)
Other financing activities	0		0
Increase (Decrease) in Cash and Cash Equivalents	0		0
Beginning Cash and Cash Equivalents	0	0	0
Ending Cash and Cash Equivalents	0	0	0
Intercompany Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities	0	0	0
Cash flows from investing activities:
Additions to oil and gas properties, including acquisitions	0	0	0
Additions to furniture, fixtures and other	0	0	0
Repayment of debt associated with merger, net of cash acquired		0
Proceeds from sale of properties	0	0	0
Other investing activities	0	0	0
Intercompany transfers	363		(3,040)
Cash flows from financing activities:
Proceeds from debt	0		0
Principal and redemption premium payments on debt	0	0	0
Proceeds from sale of common stock, net of offering costs	0	0	0
Intercompany transfers	(363)		3,040
Other financing activities	0	0	0
Increase (Decrease) in Cash and Cash Equivalents	0	0	0
Beginning Cash and Cash Equivalents	0	0	0
Ending Cash and Cash Equivalents	$ 0	$ 0	$ 0