Revenue Recognition (Disaggregated Revenue) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,824,655	$ 2,480,820	$ 2,912,770
Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	553,496	714,192	660,747
Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	1,182,697	1,684,308	2,149,223
Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	88,462	82,320	102,800
Offshore Pipeline Transportation
Disaggregation of Revenue [Line Items]
Total revenues	237,146	318,116	284,544
Offshore Pipeline Transportation | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	237,146	318,116	284,544
Offshore Pipeline Transportation | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Offshore Pipeline Transportation | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Sodium Minerals & Sulfur Services
Disaggregation of Revenue [Line Items]
Total revenues	877,769	1,105,987	1,174,434
Sodium Minerals & Sulfur Services | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Sodium Minerals & Sulfur Services | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	789,307	1,023,667	1,071,634
Sodium Minerals & Sulfur Services | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	88,462	82,320	102,800
Marine transportation
Disaggregation of Revenue [Line Items]
Total revenues	210,258	235,645	219,937
Marine transportation | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	210,258	235,645	219,937
Marine transportation | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Marine transportation | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0
Onshore Facilities & Transportation
Disaggregation of Revenue [Line Items]
Total revenues	499,482	821,072	1,233,855
Onshore Facilities & Transportation | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	106,092	160,431	156,266
Onshore Facilities & Transportation | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	393,390	660,641	1,077,589
Onshore Facilities & Transportation | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0