Consolidated Statements of Cash Flows - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash Flows From Operating Activities
Net income	$ 137,895,000	$ 127,656,000	$ 103,101,000
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	90,876,000	81,860,000	78,701,000
Deferred compensation	6,895,000	9,988,000	15,140,000
Realized and unrealized gain on long-term investments	(2,289,000)	(3,143,000)	(3,955,000)
Stock-based compensation	11,716,000	10,080,000	8,872,000
Deferred income taxes	(33,605,000)	(4,506,000)	(5,016,000)
Other non-cash items	2,158,000	3,068,000	2,240,000
Changes in assets and liabilities, excluding effects of acquisitions:
Receivables, net	(104,231,000)	(23,417,000)	4,894,000
Inventories	(79,258,000)	(15,358,000)	28,460,000
Other current assets	(1,434,000)	(13,927,000)	(680,000)
Accounts payable and accrued liabilities	44,414,000	55,739,000	(15,084,000)
Pension liabilities	(1,729,000)	(612,000)	(790,000)
Environmental and legal liabilities	450,000	(3,021,000)	2,519,000
Deferred revenues	277,000	10,809,000	26,000
Net Cash Provided By Operating Activities	72,135,000	235,216,000	218,428,000
Cash Flows From Investing Activities
Expenditures for property, plant and equipment	(194,482,000)	(125,792,000)	(105,572,000)
Proceeds from asset disposition	4,149,000
Asset acquisition (Note 20)	(3,503,000)	(2,040,000)
Business acquisitions, net of cash acquired (Note 20)	(184,473,000)	(13,519,000)	(9,000,000)
Other, net	1,480,000	2,317,000	1,905,000
Net Cash Used In Investing Activities	(376,829,000)	(139,034,000)	(112,667,000)
Cash Flows From Financing Activities
Revolving debt and bank overdrafts, net (Note 6)	2,861,000		(7,495,000)
Other debt borrowings (Note 6)	200,000,000
Other debt repayments (Note 6)	(37,858,000)	(23,571,000)	(46,429,000)
Dividends paid	(28,083,000)	(25,405,000)	(23,097,000)
Company stock repurchased	(16,969,000)	(15,253,000)	(13,184,000)
Stock option exercises	1,369,000	2,926,000	3,037,000
Other, net	(3,987,000)	(3,631,000)	(3,326,000)
Net Cash (Used In) Provided By Financing Activities	117,333,000	(64,934,000)	(90,494,000)
Effect of Exchange Rate Changes on Cash	(3,391,000)	3,307,000	(78,000)
Net Increase (Decrease) in Cash and Cash Equivalents	(190,752,000)	34,555,000	15,189,000
Cash and Cash Equivalents at Beginning of Year	349,938,000	315,383,000	300,194,000
Cash and Cash Equivalents at End of Year	159,186,000	349,938,000	315,383,000
Supplemental Cash Flow Information
Cash payments of income taxes, net of refunds/payments	92,867,000	39,017,000	29,331,000
Cash payments of interest	$ 9,542,000	$ 9,329,000	$ 12,250,000