Revenue Recognition (Disaggregated Revenue) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenues	$ 521,219	$ 539,923
Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	129,109	181,765
Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	369,601	330,134
Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	22,509	28,024
Offshore Pipeline Transportation
Disaggregation of Revenue [Line Items]
Total revenues	64,384	78,429
Offshore Pipeline Transportation | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	64,384	78,429
Offshore Pipeline Transportation | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Offshore Pipeline Transportation | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Sodium Minerals & Sulfur Services
Disaggregation of Revenue [Line Items]
Total revenues	227,287	243,390
Sodium Minerals & Sulfur Services | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Sodium Minerals & Sulfur Services | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	204,778	215,366
Sodium Minerals & Sulfur Services | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	22,509	28,024
Marine Transportation
Disaggregation of Revenue [Line Items]
Total revenues	40,331	62,346
Marine Transportation | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	40,331	62,346
Marine Transportation | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Marine Transportation | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Onshore Facilities and Transportation
Disaggregation of Revenue [Line Items]
Total revenues	189,217	155,758
Onshore Facilities and Transportation | Fee-based revenues
Disaggregation of Revenue [Line Items]
Total revenues	24,394	40,990
Onshore Facilities and Transportation | Product Sales
Disaggregation of Revenue [Line Items]
Total revenues	164,823	114,768
Onshore Facilities and Transportation | Refinery Services
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0