Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 13,414	$ (21,660)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation, depletion, amortization and accretion	68,708	64,233
Exploration expense	22,206	13,763
Stock-based compensation	6,553	3,960
Net cash for plugging wells	(214)
(Gain) loss on derivative instruments	(24,808)	20,792
Net cash payments on settled derivatives	(746)	(2,347)
Gain on sale of assets	(6)	(1,820)
Amortization of deferred financing costs	1,201	1,114
Amortization of debt discount	665	663
Changes in operating assets and liabilities:
Accounts receivable	52,182	(35,420)
Other assets	(15)	(1,397)
Accounts payable and accrued liabilities	(56,047)	8,956
Net cash provided by operating activities	83,093	50,837
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures for oil and gas properties	(177,334)	(124,045)
Capital expenditures for other property and equipment	(193)	(768)
Proceeds from sale of assets	16	10,348
Cash proceeds from merger	12,894
Change in deposits and other long-term assets	(53)
Net cash used in investing activities	(164,670)	(114,465)
CASH FLOWS FROM FINANCING ACTIVITIES
Debt issuance costs	(3,361)	(56)
Repayments of long-term debt	(182)	(181)
Proceeds from revolving credit facility	95,000	60,000
Equity issuance costs	(31)	(170)
Employee tax withholding for settlement of equity compensation awards	(6,360)	(1,140)
Net cash provided by financing activities	85,066	58,453
Net increase (decrease) in cash and cash equivalents	3,489	(5,175)
Cash and cash equivalents at beginning of period	5,959	17,224
Cash and cash equivalents at end of period	9,448	12,049
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
Cash paid for interest	25,884	24,809
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES
Asset retirement obligations incurred, including changes in estimate	750	208
Additions of other property through debt financing		174
Additions to oil and natural gas properties - changes in accounts payable, accrued liabilities, and accrued capital expenditures	41,668	26,257
Asset acquisition through stock issuance		$ 90,020
BRMR Merger consideration	$ 275,759