Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Cash Flows From Operating Activities
Net income	$ 46,895,000	$ 50,370,000	$ 40,204,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	126,041,000	112,197,000	105,338,000
Deferred compensation	2,155,000	2,155,000	4,371,000
Realized and unrealized (gains) on long-term investments	(1,898,000)	(3,323,000)	(4,314,000)
Stock-based compensation	5,999,000	5,347,000	5,741,000
Deferred income taxes	(1,395,000)	(10,291,000)	18,303,000
Goodwill and other intangibles impairment (Note 4)	6,245,000		2,038,000
Other non-cash items	(14,124,000)	2,812,000	5,123,000
Changes in assets and liabilities, excluding effects of acquisitions:
Receivables, net	23,722,000	9,036,000	32,007,000
Inventories	500,000	(37,178,000)	144,846,000
Other current assets	(7,281,000)	(1,000)	(4,528,000)
Accounts payable and accrued liabilities	(32,713,000)	33,970,000	(158,924,000)
Pension liabilities	(2,896,000)	(131,000)	(1,204,000)
Environmental and legal liabilities	(680,000)	(695,000)	(11,985,000)
Deferred revenues	(2,688,000)	(2,215,000)	(2,140,000)
Net Cash Provided By Operating Activities	147,882,000	162,053,000	174,876,000
Cash Flows From Investing Activities
Expenditures for property, plant and equipment	(122,514,000)	(122,776,000)	(260,335,000)
Proceeds from sales of assets (Note 20)	26,587,000	0	0
Other, net	6,878,000	5,831,000	1,669,000
Net Cash Used In Investing Activities	(89,049,000)	(116,945,000)	(258,666,000)
Cash Flows From Financing Activities
Revolving debt and bank overdrafts, net (Note 6)	(10,901,000)	19,886,000	104,717,000
Other debt borrowings (Note 6)	75,000,000
Other debt repayments (Note 6)	(62,857,000)	(48,571,000)	(37,858,000)
Dividends paid	(35,029,000)	(33,950,000)	(32,868,000)
Stock option exercises	104,000	1,112,000	2,795,000
Other, net	(1,757,000)	(2,997,000)	(3,502,000)
Net Cash Provided By (Used In) Financing Activities	(35,440,000)	(64,520,000)	33,284,000
Effect of Exchange Rate Changes on Cash	9,630,000	(10,746,000)	6,579,000
Net Increase (Decrease) in Cash and Cash Equivalents	33,023,000	(30,158,000)	(43,927,000)
Cash and Cash Equivalents at Beginning of Year	99,665,000	129,823,000	173,750,000
Cash and Cash Equivalents at End of Year	132,688,000	99,665,000	129,823,000
Supplemental Cash Flow Information
Cash payments of income taxes, net of refunds (Note 9)	8,499,000	(12,342,000)	29,558,000
Cash payments of interest	$ 28,682,000	$ 29,848,000	$ 27,951,000