CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities
Cash flows from operating activities	$ 53,959	$ 45,626
Cash flows from investing activities
Purchases of property, plant and equipment	(31,636)	(19,106)
Proceeds from sales of property, plant and equipment	208	211
Purchases of short-term investments	(237)	(6,787)
Proceeds from maturity of short-term investments	1,027	4,588
Other	1,203	(155)
Net cash and cash equivalents used in investing activities	(29,435)	(21,249)
Cash flows from financing activities
Advances on lines of credit and short-term debt	3,414
Taxes paid related to net share settlement	(7,264)
Debt issuance costs		(67)
Proceeds from long-term debt	91,000	7,500
Repayments of long-term debt	(137,482)	(18,701)
Net proceeds from issuance of common stock	866	2,166
Repayment of capital lease obligation	(603)	(1,238)
Dividend distribution to noncontrolling interest	(151)
Other	378
Net cash and cash equivalents used in financing activities	(49,842)	(10,340)
Effect of exchange rate changes on cash and cash equivalents	3,971	2,472
Change in cash and cash equivalents, including restricted cash	(21,347)	16,509
Cash and cash equivalents, beginning of period, including restricted cash	205,202	249,712
Cash and cash equivalents, end of period, including restricted cash	183,855	266,221
Supplemental Cash Flow Information
Interest	2,790	2,626
Taxes	4,139	7,619
Non-cash financing activities:
Decrease in accounts payable related to the purchase of property, plant and equipment	6,917	7
Noncontrolling Interest
Non-cash financing activities:
(Increase) decrease dividend accrued for noncontrolling interest	$ (1,000)	$ 1,000