Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income (loss)	$ 116,738	$ (277,353)	$ (449,305)
Adjustments to reconcile net income (loss) to net cash provided by operating activities
Provision for doubtful accounts	(2,329)	3,202	16
Depreciation, depletion and amortization	15,445	58,085	158,558
Impairment	0	256,399	409,574
Debt issuance costs amortization	57	792	558
Write off of debt issuance costs	174	0	142
Loss (gain) on derivative contracts	2,251	(5,765)	(1,094)
Cash (paid) received on settlement of derivative contracts	(2,230)	5,879	6,266
Gain on sale of assets	(18,952)	(100)	0
Stock-based compensation	1,394	3,012	4,254
Other	144	149	(187)
Changes in operating assets and liabilities increasing (decreasing) cash
Receivables	841	5,867	15,829
Prepaid expenses	2,264	452	(714)
Other current assets	0	458	(301)
Other assets and liabilities, net	(1,212)	1,134	(610)
Accounts payable and accrued expenses	(2,241)	(12,968)	(17,217)
Asset retirement obligations	(2,084)	(3,081)	(4,445)
Net cash provided by operating activities	110,260	36,162	121,324
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures for property, plant and equipment	(11,583)	(8,762)	(191,678)
Acquisitions of assets	(3,545)	(3,701)
Acquisitions of assets			236
Purchase of other property and equipment	(59)	0	0
Proceeds from sale of assets	38,160	37,556	1,593
Net cash provided by (used) in investing activities	22,973	25,093	(189,849)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from borrowings	0	59,000	211,096
Repayments of borrowings	(20,000)	(96,500)	(153,596)
Debt issuance costs	(75)	(160)	(911)
Reduction of financing lease liability	(1,024)	(1,233)	(1,374)
Proceeds from exercise of stock options	23	0	0
Cash paid for tax withholding on vested stock awards	(899)	(64)	(367)
Net cash (used in) provided by financing activities	(21,975)	(38,957)	54,848
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS and RESTRICTED CASH	111,258	22,298	(13,677)
CASH, CASH EQUIVALENTS and RESTRICTED CASH, beginning of year	28,266	5,968	19,645
CASH, CASH EQUIVALENTS and RESTRICTED CASH, end of year	$ 139,524	$ 28,266	$ 5,968