Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash Flows From Operating Activities
Net income	$ 63,382	$ 55,188
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	40,329	38,959
Deferred compensation	(859)	9,868
Realized and unrealized gains on long-term investments	(75)	(3,130)
Stock-based compensation	4,191	4,772
Deferred income taxes	1,427	223
Other non-cash items	655	2,262
Changes in assets and liabilities:
Receivables, net	(23,253)	(6,868)
Inventories	(9,740)	15,515
Other current assets	(6,077)	(3,981)
Accounts payable and accrued liabilities	(8,284)	(33,888)
Pension liabilities	(323)	(635)
Environmental and legal liabilities	(3,116)	630
Deferred revenues	243	(162)
Net Cash Provided By Operating Activities	58,500	78,753
Cash Flows From Investing Activities
Expenditures for property, plant and equipment	(54,671)	(45,084)
Asset acquisition (Note 17)	(2,040)
Other, net	2,331	2,023
Net Cash Used In Investing Activities	(54,380)	(43,061)
Cash Flows From Financing Activities
Revolving debt and bank overdrafts, net		(6,272)
Other debt repayments	(14,286)	(37,143)
Dividends paid	(12,371)	(11,285)
Company stock repurchased	(13,753)	(6,181)
Stock option exercises	392	2,163
Other, net	(415)	(2,656)
Net Cash Used In Financing Activities	(40,433)	(61,374)
Effect of Exchange Rate Changes on Cash	(6,193)	754
Net Decrease in Cash and Cash Equivalents	(42,506)	(24,928)
Cash and Cash Equivalents at Beginning of Period	315,383	300,194
Cash and Cash Equivalents at End of Period	272,877	275,266
Supplemental Cash Flow Information
Cash payments of income taxes, net of refunds/payments	7,501	11,895
Cash payments of interest	$ 4,810	$ 7,164