Business Segments - Income Statement (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Segment Reporting Information
Total revenue	$ 266,996	$ 184,293	$ 546,197	$ 385,267
Depreciation and Amortization	14,800	14,483	29,286	28,917
Operating Income (Loss) after Eliminations	21,490	7,633	46,939	23,319
Capital Expenditures and Plant Turnaround Costs	4,775	3,537	14,710	10,112
Terminalling and storage
Segment Reporting Information
Total revenue	56,631	43,849	109,436	82,088
Depreciation and Amortization	7,731	6,996	15,337	14,101
Operating Income (Loss) after Eliminations	4,068	2,576	6,935	4,884
Capital Expenditures and Plant Turnaround Costs	2,501	1,507	6,445	4,172
Transportation segment
Segment Reporting Information
Total revenue	55,832	34,926	102,542	64,741
Depreciation and Amortization	3,590	4,331	7,163	8,329
Operating Income (Loss) after Eliminations	6,155	(2,709)	7,943	(8,212)
Capital Expenditures and Plant Turnaround Costs	933	1,091	4,514	1,616
Sulfur services
Segment Reporting Information
Total revenue	56,953	38,286	116,076	73,121
Depreciation and Amortization	2,882	2,568	5,591	5,288
Operating Income (Loss) after Eliminations	12,000	8,249	26,837	16,602
Capital Expenditures and Plant Turnaround Costs	1,131	799	3,094	3,863
Natural gas liquids
Segment Reporting Information
Total revenue	97,580	67,232	218,143	165,317
Depreciation and Amortization	597	588	1,195	1,199
Operating Income (Loss) after Eliminations	3,657	3,297	13,736	17,744
Capital Expenditures and Plant Turnaround Costs	210	140	657	461
Operating Revenues
Segment Reporting Information
Total revenue	273,845	189,391	559,814	396,114
Operating Revenues | Terminalling and storage
Segment Reporting Information
Total revenue	58,410	45,524	112,793	85,358
Operating Revenues | Transportation segment
Segment Reporting Information
Total revenue	60,902	38,349	112,799	72,318
Operating Revenues | Sulfur services
Segment Reporting Information
Total revenue	56,953	38,286	116,076	73,121
Operating Revenues | Natural gas liquids
Segment Reporting Information
Total revenue	97,580	67,232	218,146	165,317
Intersegment Revenues Eliminations
Segment Reporting Information
Total revenue	(6,849)	(5,098)	(13,617)	(10,847)
Intersegment Revenues Eliminations | Terminalling and storage
Segment Reporting Information
Total revenue	(1,779)	(1,675)	(3,357)	(3,270)
Intersegment Revenues Eliminations | Transportation segment
Segment Reporting Information
Total revenue	(5,070)	(3,423)	(10,257)	(7,577)
Intersegment Revenues Eliminations | Sulfur services
Segment Reporting Information
Total revenue	0	0	0	0
Intersegment Revenues Eliminations | Natural gas liquids
Segment Reporting Information
Total revenue	0	0	(3)	0
Indirect selling, general and administrative
Segment Reporting Information
Depreciation and Amortization	0	0	0	0
Operating Income (Loss) after Eliminations	(4,390)	(3,780)	(8,512)	(7,699)
Capital Expenditures and Plant Turnaround Costs	$ 0	$ 0	$ 0	$ 0