CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Total revenues	$ 1,811,247	$ 1,750,213	$ 1,322,060
Costs and expenses:
Oil and natural gas property impairments	0	0	3
General and administrative	10,198	8,937	9,707
Depreciation, depletion and amortization	16,641	10,654	13,599
Total costs and expenses	1,803,447	1,748,805	1,320,558
Operating earnings	7,800	1,408	1,502
Other income (expense):
Loss on deconsolidation of subsidiary (Note 4)	0	0	(3,505)
Impairment of investment in unconsolidated affiliate (Note 4)	0	0	(2,500)
Gain on dissolution of investment (Note 4)	573	0	0
Interest income	2,766	2,155	1,103
Interest expense	(636)	(109)	(27)
Total other income (expense), net	2,703	2,046	(4,929)
(Losses) earnings before income taxes	10,503	3,454	(3,427)
Income tax (provision) benefit:
Current	(211)	427	(895)
Deferred	(2,085)	(936)	3,840
Income tax benefit (provision)	(2,296)	(509)	2,945
Net (losses) earnings	$ 8,207	$ 2,945	$ (482)
Earnings (losses) per share:
Basic net (losses) earnings per share (in dollars per share)	$ 1.94	$ 0.70	$ (0.11)
Diluted net (losses) earnings per common share (in dollars per share)	1.94	0.70	(0.11)
Dividends per common share (in dollars per share)	$ 0.94	$ 0.88	$ 0.88
Marketing
Revenues:
Total revenues	$ 1,748,056	$ 1,694,437	$ 1,267,275
Costs and expenses:
Cost and expenses	1,723,216	1,681,045	1,247,763
Transportation
Revenues:
Total revenues	63,191	55,776	53,358
Costs and expenses:
Cost and expenses	53,392	48,169	48,538
Oil and natural gas
Revenues:
Total revenues	0	0	1,427
Costs and expenses:
Cost and expenses	$ 0	$ 0	$ 948