CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Cash flows from operating activities
Net cash flows provided by operating activities	$ 69,889	$ 53,959
Cash flows from investing activities
Purchases of property, plant and equipment	(18,639)	(31,636)
Purchases of short-term investments	(3,153)	(237)
Proceeds from maturity of short-term investments	3,982	1,027
Other	658	1,411
Net cash and cash equivalents used in investing activities	(17,152)	(29,435)
Cash flows from financing activities
Advances on lines of credit and short-term debt	3,568	3,414
Repayments of line of credit and short-term debt	(1,461)
Taxes paid related to net share settlement	(645)	(7,264)
Proceeds from long-term debt	85,000	91,000
Repayments of long-term debt	(83,089)	(137,482)
Net proceeds from issuance of common stock	6,667	866
Repayment of finance lease obligation	(293)	(603)
Other	(120)	227
Net cash and cash equivalents provided by (used in) financing activities	9,627	(49,842)
Effect of exchange rate changes on cash and cash equivalents	(1,890)	3,971
Change in cash and cash equivalents, including restricted cash	60,474	(21,347)
Cash and cash equivalents, beginning of period, including restricted cash	241,833	205,202
Cash and cash equivalents, end of period, including restricted cash	302,307	183,855
Supplemental Cash Flow Information
Interest paid during the period	2,095	2,790
Taxes paid during the period	4,323	4,139
Non-cash investing and financing activities:
Decrease in accounts payable related to the purchase of property, plant and equipment	$ 2,366	6,917
Noncontrolling Interest
Non-cash investing and financing activities:
Increase in dividend accrued for noncontrolling interest		$ (1,000)