Note 13 - Guarantor Subsidiaries - Unaudited Interim Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities	$ 38,285	$ 18,748
Additions to properties, plants, and equipment	(21,658)	(34,654)
Other investing activities, net	(7,418)	(3,685)
Dividends paid to stockholders	(1,127)	(1,090)
Payments on debt	(2,065)	(2,782)
Other financing activity	(822)	737
Effect of exchange rate changes on cash	1,814	1,535
Changes in cash and cash equivalents	7,009	(21,191)
Cash and cash equivalents at beginning of period	169,777	155,209
Cash and cash equivalents at end of period	176,786	134,018
Consolidation, Eliminations [Member]
Cash flows from operating activities	(29,818)	40,442
Additions to properties, plants, and equipment
Other investing activities, net
Dividends paid to stockholders
Payments on debt
Other financing activity	29,818	(40,442)
Effect of exchange rate changes on cash
Changes in cash and cash equivalents
Cash and cash equivalents at beginning of period
Cash and cash equivalents at end of period
Parent Company [Member] | Reportable Legal Entities [Member]
Cash flows from operating activities	40,953	7,848
Additions to properties, plants, and equipment		(53)
Other investing activities, net	(7,479)
Dividends paid to stockholders	(1,127)	(1,090)
Payments on debt
Other financing activity	(41,096)	(9,833)
Effect of exchange rate changes on cash
Changes in cash and cash equivalents	(8,749)	(3,128)
Cash and cash equivalents at beginning of period	113,275	94,167
Cash and cash equivalents at end of period	104,526	91,039
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Cash flows from operating activities	11,508	(21,658)
Additions to properties, plants, and equipment	(7,540)	(18,552)
Other investing activities, net	61	215
Dividends paid to stockholders
Payments on debt	(1,658)	(2,556)
Other financing activity	3,024	27,189
Effect of exchange rate changes on cash
Changes in cash and cash equivalents	5,395	(15,362)
Cash and cash equivalents at beginning of period	24,388	42,692
Cash and cash equivalents at end of period	29,783	27,330
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Cash flows from operating activities	15,642	(7,884)
Additions to properties, plants, and equipment	(14,118)	(16,049)
Other investing activities, net		(3,900)
Dividends paid to stockholders
Payments on debt	(407)	(226)
Other financing activity	7,432	23,823
Effect of exchange rate changes on cash	1,814	1,535
Changes in cash and cash equivalents	10,363	(2,701)
Cash and cash equivalents at beginning of period	32,114	18,350
Cash and cash equivalents at end of period	$ 42,477	$ 15,649