Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net Income	$ 23,944	$ 8,803	$ 22,824
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	34,530	35,582	28,466
Tax liabilities, non-cash changes	(9,531)	(5,771)	5,630
Deferred income taxes	(1,179)	(5,190)	1,900
Impairments of long-lived assets and other charges	2,688	2,500	0
Stock-based compensation	2,807	2,315	2,685
Other non-cash items	1,400	2,560	(1,095)
Accounts receivable	(14,030)	(16,184)	9,074
Inventories	11,509	(9,297)	5,716
Increase (Decrease) in Other Operating Assets and Liabilities, Net	2,469	(9,138)	3,578
Accounts payable	(1,132)	(6,109)	(2,549)
Income taxes	4,695	6,366	(4,780)
Non-current tax liabilities	0	0	(297)
NET CASH PROVIDED BY OPERATING ACTIVITIES	59,349	11,627	69,252
CASH FLOWS FROM INVESTING ACTIVITIES:
Additions to property, plant and equipment	(39,543)	(112,556)	(67,980)
Proceeds from sales and maturities of investments	3,750	3,750	3,970
Purchase of investments	(950)	(3,750)	(3,750)
Proceeds from sales of fixed assets	1,815	1,873	16
Other	(18)	248	320
NET CASH USED IN INVESTING ACTIVITIES	(34,946)	(110,435)	(67,424)
CASH FLOWS FROM FINANCING ACTIVITIES:
Cash dividends paid	(19,082)	(19,351)	(550)
Cash paid for common stock repurchase	(19,638)	(21,790)	(8,133)
Proceeds from exercise of stock options	7,265	7,423	2,865
Excess tax benefits from exercise of stock options	107	106	252
NET CASH USED IN FINANCING ACTIVITIES	(31,348)	(33,612)	(5,566)
Effect of exchange rate changes on cash	(3,470)	(4,430)	(325)
Net increase (decrease) in cash and cash equivalents	(10,415)	(136,850)	(4,063)
Cash and cash equivalents at the beginning of the period	62,451	199,301	203,364
Cash and cash equivalents at the end of period	$ 52,036	$ 62,451	$ 199,301