Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities:
Net income (loss)	$ 564	$ 4,008	$ 14,227	$ (50,230)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Impairment expense	833	92	833	66,740
Depreciation, depletion and amortization	12,842	10,330	33,362	28,258
Accretion of asset retirement obligations	44	72	128	378
Settlement of asset retirement obligations			(79)	0
Gain on sale of oil and gas properties	(4,096)	(2,157)	(4,608)	(3,848)
Total loss (gain) on derivative contracts, net	17,481	3,663	33,606	(4,137)
Operating portion of net cash paid in settlement of derivative contracts			(13,643)	229
Stock-based compensation			5,535	4,645
Deferred income taxes			119	(10,046)
Write-off of deferred financing costs	0	0	0	526
Amortization of deferred financing costs	100	100	228	195
Changes in assets and liabilities:
(Increase) decrease in accounts receivable			(1,476)	6,964
Increase in prepaid expenses and other current assets			(372)	(455)
Increase (decrease) in accounts payable and accrued expenses			3,939	(11,522)
Increase (decrease) in revenues and royalties payable			26,572	(4,019)
Increase (decrease) in advances			(1,816)	506
Net cash provided by operating activities			96,555	24,184
Cash flows from investing activities:
Bold Contribution Agreement, net of cash acquired			0	(55,609)
Additions to oil and gas properties			(120,124)	(29,958)
Additions to office and other equipment			(121)	(139)
Proceeds from sales of oil and gas properties			5,840	5,054
Net cash used in investing activities			(114,405)	(80,652)
Cash flows from financing activities:
Proceeds from borrowings			70,308	70,000
Repayments of borrowings			(60,308)	(11,193)
Cash paid related to the exchange and cancellation of Class A Common Stock			(1,402)	(324)
Deferred financing costs			(274)	(1,168)
Net cash provided by financing activities			8,324	57,315
Net (decrease) increase in cash			(9,526)	847
Cash at beginning of period			22,955	10,200
Cash at end of period	$ 13,429	$ 11,047	13,429	11,047
Cash paid for:
Interest			1,480	1,555
Non-cash investing and financing activities:
Accrued capital expenditures			11,314	19,519
Asset retirement obligations			(120)	83
Class A Common Stock
Non-cash investing and financing activities:
Common stock issued in Bold Contribution Agreement			0	2,037
Class B Common Stock
Non-cash investing and financing activities:
Common stock issued in Bold Contribution Agreement			$ 0	$ 489,842