Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
OPERATING ACTIVITIES:
Net loss	$ (2,964)	$ 254	$ (3,996)	$ (3,406)
Deferred income taxes	397	(618)	(1,332)	(2,270)
Equity income – Sunrise Energy	(63)	(1,231)	(63)	(1,286)
Depreciation, depletion and amortization	9,715	10,217	20,022	20,844
Unrealized gain on marketable securities			0	(14)
Amortization of debt issuance costs	641	609	1,251	1,076
Asset retirement obligations accretion	373	343	736	676
Stock-based compensation			567	636
Change in current assets and liabilities:
Accounts receivable			28	12,094
Inventory			(7,682)	(13,715)
Parts and supplies			(392)	2,207
Prepaid income taxes			0	586
Prepaid expenses			(108)	(1,004)
Accounts payable and accrued liabilities			5,652	(6,035)
Other			198	3,896
Cash provided by operating activities			12,888	17,174
INVESTING ACTIVITIES:
Distribution from Sunrise Energy			0	1,012
Capital expenditures			(10,837)	(10,032)
Proceeds from sale of equipment			0	56
Proceeds from sale of marketable securities			0	2,310
Proceeds from maturities of certificates of deposit			0	245
Cash used in investing activities			(10,837)	(6,409)
FINANCING ACTIVITIES:
Payments on bank debt			(18,875)	(26,287)
Borrowings of bank debt			(11,250)	(7,250)
Proceeds from PPP loan			0	10,000
Debt issuance costs			(418)	(1,903)
Taxes paid on vesting of RSUs			(2)	(17)
Dividends paid			0	(1,236)
Cash used in financing activities			(8,045)	(12,193)
Decrease in cash, cash equivalents, and restricted cash			(5,994)	(1,428)
Cash, cash equivalents, and restricted cash, beginning of period			12,071	13,311
Cash, cash equivalents, and restricted cash, end of period	6,077	11,883	6,077	11,883
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH CONSIST OF THE FOLLOWING:
Cash and cash equivalents	2,582	7,375	2,582	7,375
Restricted cash	3,495	4,508	3,495	4,508
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	$ 6,077	$ 11,883	6,077	11,883
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest			4,446	5,571
SUPPLEMENTAL NON-CASH FLOW INFORMATION:
Change in capital expenditures included in accounts payable and prepaid expense			3,613	1,527
Interest Rate Swap [Member]
OPERATING ACTIVITIES:
Change in fair value of derivative			(1,614)	1,976
Fuel Hedge [Member]
OPERATING ACTIVITIES:
Change in fair value of derivative			$ (379)	$ 913