Business Segment Information (Schedule of Total Assets and Total Growth and Maintenance Capital Expenditures by Reportable Segment) (Details)	12 Months Ended
	Dec. 31, 2025 USD ($)	Dec. 31, 2024 USD ($)
Segment Reporting Information [Line Items]
Assets	$ 4,860,703,000	$ 7,037,692,000
Capital Expenditures	145,725,000	376,427,000
Disposal Group, Including Discontinued Operation, Assets, Adjusted	$ 0	$ 2,207,420,000
Offshore Pipeline Transportation
Segment Reporting Information [Line Items]
Costs incurred, percentage	1	1
Operating Segments
Segment Reporting Information [Line Items]
Assets	$ 4,827,040,000	$ 4,790,616,000
Capital Expenditures	144,567,000	364,383,000
Operating Segments | Offshore Pipeline Transportation
Segment Reporting Information [Line Items]
Assets	2,755,595,000	2,748,296,000
Capital Expenditures	85,728,000	255,640,000
Operating Segments | Marine Transportation
Segment Reporting Information [Line Items]
Assets	618,474,000	641,082,000
Capital Expenditures	52,383,000	91,752,000
Operating Segments | Onshore Transportation and Services
Segment Reporting Information [Line Items]
Assets	1,452,971,000	1,401,238,000
Capital Expenditures	6,456,000	16,991,000
Other assets
Segment Reporting Information [Line Items]
Capital Expenditures	1,158,000	12,044,000
Segment Reporting, Reconciling Item, Corporate Nonsegment
Segment Reporting Information [Line Items]
Assets	$ 33,663,000	$ 39,656,000