Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019
Disaggregation of Revenue
Revenues	$ 152,533	$ 177,900	$ 492,054		$ 605,256
Lubricant product sales
Disaggregation of Revenue
Revenues	25,659	32,553	80,119		94,991
Throughput and storage
Disaggregation of Revenue
Revenues	20,706	21,193	61,088	[1]	65,674	[1]
Natural gas liquids
Disaggregation of Revenue
Revenues	52,350	60,871	164,860		234,743
Sulfur services
Disaggregation of Revenue
Revenues	2,915	2,859	8,744		8,576
Terminalling and storage segment
Disaggregation of Revenue
Revenues	46,365	53,746	141,207		160,665
Terminalling and storage segment | Lubricant product sales
Disaggregation of Revenue
Revenues	25,659	32,553	80,119		94,991
Terminalling and storage segment | Throughput and storage
Disaggregation of Revenue
Revenues	20,706	21,193	61,088		65,674
Natural gas liquids segment
Disaggregation of Revenue
Revenues	52,350	60,871	164,860		234,743
Natural gas liquids segment | Natural gas liquids
Disaggregation of Revenue
Revenues	52,350	60,871	164,860		234,743
Sulfur services segment
Disaggregation of Revenue
Revenues	21,880	23,072	83,623		90,521
Sulfur services segment | Sulfur product sales
Disaggregation of Revenue
Revenues	6,161	6,398	19,010		24,554
Sulfur services segment | Fertilizer product sales
Disaggregation of Revenue
Revenues	12,804	13,815	55,869		57,391
Sulfur services segment | Sulfur services
Disaggregation of Revenue
Revenues	2,915	2,859	8,744		8,576
Transportation segment
Disaggregation of Revenue
Revenues	31,938	40,211	102,364		119,327
Transportation segment | Land transportation
Disaggregation of Revenue
Revenues	21,879	25,059	65,986		74,675
Transportation segment | Inland transportation
Disaggregation of Revenue
Revenues	9,294	13,588	33,611		40,253
Transportation segment | Offshore transportation
Disaggregation of Revenue
Revenues	$ 765	$ 1,564	$ 2,767		$ 4,399

[1] Related Party Transactions Included Above Three Months EndedNine Months EndedSeptember 30,September 30,2020201920202019Revenues:*    Terminalling and storage$15,902 $17,538 $47,718 $53,987 Transportation5,514 6,442 16,801 17,941 Product Sales69 122 199 829 Costs and expenses:* Cost of products sold: (excluding depreciation and amortization) Sulfur services2,512 2,620 7,833 8,078 Terminalling and storage4,303 6,300 14,329 19,412 Expenses:Operating expenses18,915 21,745 60,126 66,409 Selling, general and administrative8,356 8,358 24,723 24,148