CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Cash flows from operating activities	$ 88,381	$ 65,437
Cash flows from investing activities
Purchases of property, plant and equipment	(52,990)	(43,883)
Purchases of short-term investments	(10,171)	(9,821)
Proceeds from maturity of short-term investments	7,289	24,108
Other	2,245	(554)
Net cash and cash equivalents used in investing activities	(53,627)	(30,150)
Cash flows from financing activities
Advances on lines of credit and short-term debt	3,414	392
Taxes paid related to net share settlement	(8,617)	(128)
Proceeds from long-term debt	189,656	7,500
Repayments of long-term debt	(272,170)	(34,404)
Net proceeds from issuance of common stock	3,009	6,666
Proceeds from capital lease obligation	1,775
Repayment of capital lease obligation		(378)
Dividend distribution to noncontrolling interest	(1,151)	(3,282)
Other	654	225
Net cash and cash equivalents used in financing activities	(83,430)	(23,409)
Effect of exchange rate changes on cash and cash equivalents	(2,753)	6,331
Change in cash and cash equivalents, including restricted cash	(51,429)	18,209
Cash and cash equivalents, beginning of period, including restricted cash	205,202	249,712
Cash and cash equivalents, end of period, including restricted cash	153,773	267,921
Supplemental Cash Flow Information
Interest	5,334	7,079
Taxes	16,643	20,036
Non-cash financing activities:
Decrease/(increase) in accounts payable related to the purchase of property, plant and equipment	5,452	(13,840)
Noncontrolling Interest
Non-cash financing activities:
Increase in dividend accrued for noncontrolling interest	$ (1,427)	$ (1,449)