Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020		Jun. 30, 2019
Disaggregation of Revenue
Revenues	$ 140,638	$ 187,323	$ 339,521		$ 427,356
Lubricant product sales
Disaggregation of Revenue
Revenues	25,526	31,371	54,460		62,438
Throughput and storage
Disaggregation of Revenue
Revenues	19,908	21,377	40,382	[1]	44,481	[1]
Natural gas liquids
Disaggregation of Revenue
Revenues	30,299	57,398	112,510		173,872
Sulfur services
Disaggregation of Revenue
Revenues	2,914	2,858	5,829		5,717
Terminalling and storage segment
Disaggregation of Revenue
Revenues	45,434	52,748	94,842		106,919
Terminalling and storage segment | Lubricant product sales
Disaggregation of Revenue
Revenues	25,526	31,371	54,460		62,438
Terminalling and storage segment | Throughput and storage
Disaggregation of Revenue
Revenues	19,908	21,377	40,382		44,481
Natural gas liquids segment
Disaggregation of Revenue
Revenues	30,299	57,398	112,510		173,872
Natural gas liquids segment | Natural gas liquids
Disaggregation of Revenue
Revenues	30,299	57,398	112,510		173,872
Sulfur services segment
Disaggregation of Revenue
Revenues	33,420	35,856	61,743		67,449
Sulfur services segment | Sulfur product sales
Disaggregation of Revenue
Revenues	6,367	8,204	12,849		18,156
Sulfur services segment | Fertilizer product sales
Disaggregation of Revenue
Revenues	24,139	24,794	43,065		43,576
Sulfur services segment | Sulfur services
Disaggregation of Revenue
Revenues	2,914	2,858	5,829		5,717
Transportation segment
Disaggregation of Revenue
Revenues	31,485	41,321	70,426		79,116
Transportation segment | Land transportation
Disaggregation of Revenue
Revenues	19,873	25,497	44,107		49,616
Transportation segment | Inland transportation
Disaggregation of Revenue
Revenues	10,611	14,188	24,317		26,665
Transportation segment | Offshore transportation
Disaggregation of Revenue
Revenues	$ 1,001	$ 1,636	$ 2,002		$ 2,835

[1] Related Party Transactions Included Above Three Months EndedSix Months EndedJune 30,June 30,2020201920202019Revenues:*    Terminalling and storage$15,942  $17,477  $31,816  $36,449  Transportation5,393  5,856  11,287  11,499  Product Sales38  286  130  707  Costs and expenses:* Cost of products sold: (excluding depreciation and amortization) Sulfur services2,554  2,884  5,321  5,458  Terminalling and storage4,249  7,203  10,026  13,112  Expenses:Operating expenses19,440  24,407  41,211  46,943  Selling, general and administrative8,055  8,558  16,367  17,093