Business Segment Information (Schedule of Segment Information) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Segment Reporting Information [Line Items]
Total Segment Margin	$ 181,098	$ 195,129
Revenues	770,105	790,612
Offshore pipeline transportation
Segment Reporting Information [Line Items]
Revenues	101,990	91,395
Soda and sulfur services
Segment Reporting Information [Line Items]
Revenues	400,948	444,648
Onshore facilities and transportation
Segment Reporting Information [Line Items]
Revenues	183,593	171,343
Marine transportation
Segment Reporting Information [Line Items]
Revenues	83,574	83,226
Operating Segments
Segment Reporting Information [Line Items]
Total Segment Margin	181,098	195,129
Capital expenditures	101,057	83,025
Revenues	770,105	790,612
Operating Segments | Offshore pipeline transportation
Segment Reporting Information [Line Items]
Total Segment Margin	97,806	97,938
Capital expenditures	63,626	52,053
Revenues	101,990	91,395
Operating Segments | Soda and sulfur services
Segment Reporting Information [Line Items]
Total Segment Margin	45,382	66,107
Capital expenditures	18,600	19,985
Revenues	402,954	446,906
Operating Segments | Onshore facilities and transportation
Segment Reporting Information [Line Items]
Total Segment Margin	6,547	5,390
Capital expenditures	6,521	1,930
Revenues	181,587	169,085
Operating Segments | Marine transportation
Segment Reporting Information [Line Items]
Total Segment Margin	31,363	25,694
Capital expenditures	12,310	9,057
Revenues	83,574	83,226
Intersegment
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment | Offshore pipeline transportation
Segment Reporting Information [Line Items]
Revenues	0	0
Intersegment | Soda and sulfur services
Segment Reporting Information [Line Items]
Revenues	(2,006)	(2,258)
Intersegment | Onshore facilities and transportation
Segment Reporting Information [Line Items]
Revenues	2,006	2,258
Intersegment | Marine transportation
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0