CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating Activities
Net income	$ 154,115	$ 105,406	$ 266
Adjustments to reconcile net income to net cash provided by operating activities, net of effects of acquisitions:
Depreciation	91,543	86,291	76,883
Amortization of intangibles	18,041	18,353	18,798
Amortization of debt issuance costs	521	522	514
Share-based compensation	20,535	20,736	18,609
Gain on disposal of property, plant and equipment	(24,429)	(636)	1,969
Deferred income taxes	9,904	3,674	25,326
Other	(187)	(2,335)	(1,814)
Changes in operating assets:
Accounts receivable	(30,775)	(29,478)	22,261
Inventories	(11,325)	(2,154)	(17,199)
Prepaid expenses and other current assets	(6,630)	(11,119)	1,494
Changes in operating liabilities:
Accounts payable	3,513	9,977	17,313
Accrued liabilities	7,369	(13,445)	13,079
Other liabilities	(2,694)	345	4,495
Income taxes payable (refundable)	271	(571)	(871)
Net cash and cash equivalents provided by operating activities	229,772	185,566	181,123
Investing Activities
Acquisitions, net of cash acquired	(33,028)	(41)
Purchases of short-term investments	(19,271)	(15,901)	(12,205)
Sales of short-term investments	21,847	12,576	38,600
Purchases of property, plant and equipment	(98,505)	(87,507)	(111,161)
Proceeds from sales of property, plant and equipment	29,366	429	1,219
Receipt of subsidies and grants			6,968
Other	(835)	1,500	(2,333)
Net cash and cash equivalents used in investing activities	(100,426)	(88,944)	(78,912)
Financing Activities
Advances on lines of credit and short-term debt	9,954	9,151	3,375
Repayments on lines of credit and short-term debt	(7,362)	(2,797)	(2,391)
Taxes related to net share settlement	(4,432)	(11,294)	(278)
Net proceeds from the issuance of common stock	11,901	4,862	13,606
Proceeds from long-term debt	405,540	465,656	44,500
Debt issuance costs	(223)		(111)
Repayments of long-term debt	(522,860)	(522,473)	(204,374)
Repayments of finance lease obligations	(1,082)	1,198	(587)
Purchase of treasury stock			(8,745)
Capital contribution from noncontrolling interest		6,255
Dividend distribution to noncontrolling interest	(3,818)	(2,694)	(5,754)
Other	(50)	225	2,575
Net cash and cash equivalents used in financing activities	(112,432)	(51,911)	(158,184)
Effect of exchange rate changes on cash and cash equivalents, including restricted cash	760	(8,078)	11,461
Increase (decrease) in cash and cash equivalents, including restricted cash	17,674	36,633	(44,512)
Cash and cash equivalents, beginning of year, including restricted cash	241,833	205,200	249,712
Cash and cash equivalents, end of year, including restricted cash	259,507	241,833	205,200
Cash paid during the year for:
Interest	7,235	9,962	13,547
Income taxes	37,158	33,265	30,447
Non-cash activities:
(Increase) decrease property, plant and equipment purchased on accounts payable	$ 2,260	$ 7,766	(14,081)
Noncontrolling Interest
Non-cash activities:
Decrease (increase) in dividend accrued for noncontrolling interest			$ 1,008