Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
OPERATING ACTIVITIES:
Net loss	$ 1,923		$ (3,723)	$ (1,483)	$ (67)
Deferred income taxes	(387)		(3,047)	(2,657)	(2,741)
Equity (income) loss – Sunrise Energy	119		184	(1,167)	350
Cash distribution - Sunrise Energy				1,125	0
Depreciation, depletion and amortization	9,315		11,778	30,159	35,612
Asset impairment	1,799		0	1,799	0
Loss (gain) on sale of assets				38	(99)
Unrealized gain on marketable securities				(14)	(334)
Gain on sale of royalty interests in oil properties				0	(2,949)
Amortization and write off of debt issuance costs	610		543	1,686	1,628
Asset retirement obligations accretion	348		320	1,024	943
Stock-based compensation				927	1,438
Change in current assets and liabilities:
Accounts receivable				9,742	(3,294)
Inventory				(9,247)	(6,455)
Parts and supplies				2,603	(2,396)
Prepaid income taxes				1,562	992
Prepaid expenses				1,744	3,800
Accounts payable and accrued liabilities				(5,488)	6,877
Cash provided by operating activities				34,109	36,323
INVESTING ACTIVITIES:
Investment in Sunrise Energy				(113)	0
Capital expenditures				(13,991)	(27,269)
Proceeds from sale of equipment				56	129
Proceeds from sale of royalty interests in oil properties				0	2,949
Proceeds from sale of marketable securities				2,310	0
Maturities of certificates of deposit				245	245
Cash used in investing activities				(11,493)	(23,946)
FINANCING ACTIVITIES:
Payments on bank debt				(40,475)	(34,713)
Borrowings of bank debt				7,250	18,250
Proceeds from PPP note				10,000	0
Payments of debt issuance costs				(1,903)	(1,183)
Taxes paid on vesting of restricted stock units				(18)	(14)
Dividends paid				(1,236)	(3,724)
Cash used in financing activities				(26,382)	(21,384)
Decrease in cash, cash equivalents, and restricted cash				(3,766)	(9,007)
Cash, cash equivalents, and restricted cash, beginning of period		$ 11,087		13,311	20,094	$ 20,094
Cash, cash equivalents, and restricted cash, end of period	9,545	13,311	11,087	9,545	11,087	13,311
CASH, CASH EQUIVALENTS, AND RESTRICTED CASH CONSIST OF THE FOLLOWING:
Cash and cash equivalents	5,302	8,799	6,361	5,302	6,361	8,799
Restricted cash	4,243	$ 4,512	4,726	4,243	4,726	$ 4,512
Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Ending Balance	$ 9,545		$ 11,087	9,545	11,087
SUPPLEMENTAL CASH FLOW INFORMATION:
Cash paid for interest				8,246	8,900
SUPPLEMENTAL NON-CASH FLOW INFORMATION:
Capital expenditures included in accounts payable and prepaid expense				968	2,018
Right-of-use assets acquired in exchange for operating lease liabilities				645	882
Interest Rate Swap [Member]
OPERATING ACTIVITIES:
Change in fair value of derivative				981	3,018
Fuel Hedge [Member]
OPERATING ACTIVITIES:
Change in fair value of derivative				$ 775	$ 0