Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (38,130)	$ (20,598)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, depletion and amortization	36,162	25,472
Stock-based compensation	2,713	639
Share based payments	(601)	0
Deferred taxes	(6,432)	(11,262)
Loss (gain) on derivative financial instruments	36,620	(14,162)
Settlements of derivative financial instruments	(8,676)	2,682
Impairment of oil and natural gas properties	0	27,081
Loss on abandoned property and equipment	170	0
Non-cash interest expense	3,544	3,434
Unrealized loss (gain) on warrants	2,615	(2,884)
Changes in operating assets and liabilities:
Accounts receivable	(254)	(1,308)
Prepaid expenses and other assets	(1,159)	(3,010)
Accounts payable and accrued expenses	12,179	11,028
Net cash provided by operating activities	38,751	17,112
Cash flows from investing activities
Acquisition of oil and gas properties	(2,862)	(108,179)
Development of oil and gas properties	(66,761)	(37,750)
Purchases of other property and equipment	(1,498)	(1,522)
Net cash used in investing activities	(71,121)	(147,451)
Cash flows from financing activities
Proceeds from borrowings and related party borrowings	290,744	76,079
Payments on borrowings and related party borrowings	(255,452)	(19,503)
Proceeds from the sale of preferred stock	0	77,800
Cost to issue equity	0	(1,000)
Payments of debt issuance costs	0	(2,537)
Net cash provided by financing activities	35,292	130,839
Net increase in cash and cash equivalents	2,922	500
Cash and cash equivalents, beginning of the period	2,538	6,068
Cash and cash equivalents, end of the period	5,460	6,568
Supplemental information:
Cash paid for taxes	1,147	2,240
Cash paid for interest	6,143	10,674
Non-cash investing and financing activities:
Preferred stock issued for asset acquisition	0	10,795
Cost to issue equity included in accounts payable	0	1,500
Asset retirement obligation	183	2,235
Increase in liabilities for capital expenditures	$ 12,425	$ 1,358