Condensed Consolidated Statement of Cash Flows - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Operating activities:
Net income (loss)	$ (3,660)	$ 7,000
Deferred income taxes	(1,652)	193
Equity (income) loss	(55)	34
DD&A	10,627	11,738
Unrealized gain on marketable securities	(14)	(303)
Gain on sale of royalty interests in oil properties		(2,500)
Amortization and write off of deferred financing costs	467	543
Accretion of ARO	333	309
Stock-based compensation	319	494
Change in current assets and liabilities:
Accounts receivable	12,885	2,823
Inventory	(9,113)	(2,674)
Parts and supplies	889	(1,084)
Prepaid income taxes	581	1,340
Prepaid expenses	159	1,701
Accounts payable and accrued liabilities	(1,691)	2,325
Other	2,277	(2,105)
Cash provided by operating activities	16,256	20,847
Investing activities:
Investment in affiliate	(112)
Capital expenditures	(6,022)	(8,840)
Proceeds from sale of royalty interests in oil properties		2,500
Proceeds from sale of marketable securities	2,310
Proceeds from maturities of certificates of deposit	245
Cash used in investing activities	(3,579)	(6,340)
Financing activities:
Payments of bank debt	(12,100)	(20,013)
Dividends	(1,236)	(1,241)
Cash used in financing activities	(13,336)	(21,254)
Decrease in cash ,cash equivalents, and restricted cash	(659)	(6,747)
Cash, cash equivalents, and restricted cash beginning of year	13,311	20,094	$ 20,094
Cash, cash equivalents, and restricted cash end of year	12,652	13,347	13,311
Cash, cash equivalents, and restricted cash:
Cash				$ 7,918	$ 8,799	$ 8,690
Restricted cash				4,734	4,512	4,657
Cash, cash equivalents, and restricted cash, Total	12,652	13,347	$ 13,311	$ 12,652	$ 13,311	$ 13,347
Supplemental cash flow information:
Cash paid for interest	2,707	3,058
Cash received from income taxes	1,105	1,569
Capital expenditures included in accounts payable and prepaid expense	3,516	3,250
Right-to-use asset due to adoption of ASU 2016-02		426
Interest Rate Swap [Member]
Operating activities:
Change in fair value of derivative	2,593	$ 1,013
Fuel Hedge [Member]
Operating activities:
Change in fair value of derivative	$ 1,311