Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash Flows From Operating Activities
Net income	$ 27,539	$ 24,978
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	20,023	19,403
Deferred compensation	(7,323)	7,473
Realized and unrealized (gains) losses on long-term investments	3,875	(2,404)
Stock-based compensation	1,202	2,596
Deferred income taxes	131	(1,857)
Other non-cash items	395	1,443
Changes in assets and liabilities:
Receivables, net	(30,767)	(17,434)
Inventories	(447)	16,231
Other current assets	(3,180)	(3,247)
Accounts payable and accrued liabilities	(16,583)	(42,279)
Pension liabilities	(236)	(392)
Environmental and legal liabilities	(947)	6
Deferred revenues	(157)	(81)
Net Cash (Used In) Provided By Operating Activities	(6,475)	4,436
Cash Flows From Investing Activities
Expenditures for property, plant and equipment	(33,202)	(25,741)
Asset acquisition (Note 17)	(2,040)
Other, net	2,331	2,037
Net Cash Used In Investing Activities	(32,911)	(23,704)
Cash Flows From Financing Activities
Revolving debt and bank overdrafts, net		(4,230)
Dividends paid	(6,202)	(5,643)
Company stock repurchased	(7,243)	(77)
Stock option exercises	155	1,890
Other, net	(1,128)	(2,718)
Net Cash Used In Financing Activities	(14,418)	(10,778)
Effect of Exchange Rate Changes on Cash	(7,240)	(689)
Net Decrease in Cash and Cash Equivalents	(61,044)	(30,735)
Cash and Cash Equivalents at Beginning of Period	315,383	300,194
Cash and Cash Equivalents at End of Period	254,339	269,459
Supplemental Cash Flow Information
Cash payments of income taxes, net of refunds/payments	3,316	3,018
Cash payments of interest	$ 2,122	$ 2,131