CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
CASH FLOWS FROM OPERATING ACTIVITIES
Net Income (Loss)	$ 35,043	$ (12,670)
Adjustments to reconcile net loss to net cash provided by operating activities
Provision for doubtful accounts	21	283
Depreciation, depletion, and amortization	3,999	27,489
Impairment	0	7,970
Debt issuance costs amortization	16	159
(Gain) loss on derivative contracts	0	(10,226)
Cash received on settlement of derivative contracts	0	4,087
(Gain) loss on sale of assets	(19,713)	0
Stock-based compensation	235	169
Other	35	156
Changes in operating assets and liabilities	(5,305)	686
Net cash provided by (used in) operating activities	14,331	18,103
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures for property, plant and equipment	(3,094)	(5,452)
Purchase of other property and equipment	(59)	0
Proceeds from sale of assets	37,238	989
Net cash provided by (used in) investing activities	34,085	(4,463)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from borrowings	0	21,000
Repayments of borrowings	0	(32,500)
Reduction of financing lease liability	(74)	(366)
Debt issuance costs	(74)	0
Cash paid for tax obligations on vested stock awards	(19)	(1)
Net cash provided by (used in) financing activities	(167)	(11,867)
NET INCREASE (DECREASE) IN CASH, CASH EQUIVALENTS and RESTRICTED CASH	48,249	1,773
CASH, CASH EQUIVALENTS and RESTRICTED CASH, beginning of year	28,266	5,968
CASH, CASH EQUIVALENTS and RESTRICTED CASH, end of period	76,515	7,741
Supplemental Disclosure of Cash Flow Information
Cash paid for interest, net of amounts capitalized	(92)	(540)
Cash received for income taxes	0	616
Supplemental Disclosure of Noncash Investing and Financing Activities
Purchase of PP&E in accounts payable	1,342	1,066
Right-of-use assets obtained in exchange for financing lease obligations	363	67
Carrying value of properties exchanged	$ 0	$ 3,890