Supplemental Cash Flow Information (Net Changes in Components of Operating Assets and Liabilities) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
(Increase) decrease in:
Accounts receivable	$ (19,956,000)	$ (4,548,000)
Inventories	16,913,000	(5,833,000)
Deferred charges	626,000	(14,052,000)
Other current assets	(12,834,000)	(3,331,000)
Increase (decrease) in:
Accounts payable	5,789,000	(744,000)
Accrued liabilities	3,274,000	(3,860,000)
Net changes in components of operating assets and liabilities	$ (6,188,000)	$ (32,368,000)