Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 31,762	$ 18,826	$ 8,525
Adjustments to reconcile net income to net cash provided by operating activities
Depreciation, depletion, amortization and accretion	156,552	134,940	119,362
Exploration expense	47,775	28,324	31,417
Stock-based compensation	8,784	7,891	9,301
Net cash for plugging wells	(1,044)
(Gain) loss on derivative instruments	(48,596)	21,169	(45,365)
Net cash receipts (payments) on settled derivatives	20,323	(26,985)	(2,224)
Gain on sale of assets	(601)	(1,815)	(179)
Amortization of deferred financing costs	2,781	2,256	2,098
Amortization of debt discount	1,330	1,327	1,324
Changes in operating assets and liabilities:
Accounts receivable	67,652	(42,879)	(31,780)
Other assets	1,893	(2,192)	1,863
Accounts payable and accrued liabilities	(33,182)	84,231	18,404
Net cash provided by operating activities	255,429	225,093	112,746
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures for oil and gas properties	(349,710)	(275,601)	(291,779)
Capital expenditures for other property and equipment	(632)	(1,007)	(2,007)
Proceeds from sale of assets	1,959	10,358	1,317
Cash acquired in merger	12,894
Change in deposits and other long-term assets	(53)
Net cash used in investing activities	(335,542)	(266,250)	(292,469)
CASH FLOWS FROM FINANCING ACTIVITIES
Debt issuance costs	(4,264)	(497)	(1,750)
Repayments of long-term debt	(321)	(506)	(453)
Proceeds from revolving credit facility	97,500	32,500
Equity issuance costs	(30)	(344)	(44)
Employee tax withholding for settlement of equity compensation awards	(6,675)	(1,261)	(2,035)
Net cash provided by (used in) financing activities	86,210	29,892	(4,282)
Net increase (decrease) in cash and cash equivalents	6,097	(11,265)	(184,005)
Cash and cash equivalents at beginning of period	5,959	17,224	201,229
Cash and cash equivalents at end of period	12,056	5,959	17,224
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest	59,552	51,101	47,362
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Asset retirement obligations incurred, including changes in estimate	2,898	418	679
Additions of other property through debt financing		173	183
Additions to oil and natural gas properties - changes in accounts payable, accrued liabilities, and accrued capital expenditures	17,725	(15,269)	22,264
Assets held for sale			$ (262)
Asset acquisition through stock issuance		$ 90,020
BRMR Merger consideration	$ 275,759