Note 17 - Guarantor Subsidiaries - Unaudited Interim Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flows from operating activities	$ 94,221	$ 115,878	$ 225,328
Additions to properties, plants, and equipment	(136,933)	(98,038)	(164,788)
Purchase of other companies, net of cash acquired	(139,326)		(2,730)
Other investing activities, net	39,711	1,475	(29,946)
Dividends paid to stockholders	(4,945)	(4,528)	(4,419)
Borrowings under debt arrangements	102,024
Repayments of debt	(113,375)	(6,986)	(11,156)
Other financing activity	1,412	6,266	3,554
Effect of exchange rate changes on cash	(1,515)	1,095	(74)
Changes in cash, cash equivalents and restricted cash and cash equivalents	(158,725)	15,162	15,769
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	187,139	171,977	156,208
Cash, cash equivalents and restricted cash and cash equivalents at end of year	28,414	187,139	171,977
Reportable Legal Entities [Member] | Parent Company [Member]
Cash flows from operating activities	(23,136)	(134,900)	85,665
Additions to properties, plants, and equipment			(348)
Purchase of other companies, net of cash acquired	(139,326)		(2,730)
Other investing activities, net	(186,615)	132,118	(30,584)
Dividends paid to stockholders	(4,945)	(4,528)	(4,419)
Borrowings under debt arrangements	102,024
Repayments of debt	(106,036)
Other financing activity	260,422	(2,087)	(28,476)
Effect of exchange rate changes on cash
Changes in cash, cash equivalents and restricted cash and cash equivalents	(97,612)	(9,397)	19,108
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	103,878	113,275	94,167
Cash, cash equivalents and restricted cash and cash equivalents at end of year	6,266	103,878	113,275
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Cash flows from operating activities	38,116	(98,046)	82,778
Additions to properties, plants, and equipment	(90,578)	(46,570)	(93,541)
Purchase of other companies, net of cash acquired
Other investing activities, net	1,715	8,119	305
Dividends paid to stockholders
Borrowings under debt arrangements
Repayments of debt	(5,550)	(5,242)	(10,174)
Other financing activity	33,933	147,199	3,529
Effect of exchange rate changes on cash
Changes in cash, cash equivalents and restricted cash and cash equivalents	(22,364)	5,460	(17,103)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	32,048	26,588	43,691
Cash, cash equivalents and restricted cash and cash equivalents at end of year	9,684	32,048	26,588
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities	35,508	120,027	76,491
Additions to properties, plants, and equipment	(46,354)	(51,468)	(70,899)
Purchase of other companies, net of cash acquired
Other investing activities, net	5,072		333
Dividends paid to stockholders
Borrowings under debt arrangements
Repayments of debt	(1,789)	(1,744)	(982)
Other financing activity	(29,671)	(48,811)	8,895
Effect of exchange rate changes on cash	(1,515)	1,095	(74)
Changes in cash, cash equivalents and restricted cash and cash equivalents	(38,749)	19,099	13,764
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	51,213	32,114	18,350
Cash, cash equivalents and restricted cash and cash equivalents at end of year	12,464	51,213	32,114
Consolidation, Eliminations [Member]
Cash flows from operating activities	43,733	228,797	(19,606)
Additions to properties, plants, and equipment
Purchase of other companies, net of cash acquired
Other investing activities, net	219,539	(138,762)
Dividends paid to stockholders
Borrowings under debt arrangements
Repayments of debt
Other financing activity	(263,272)	(90,035)	19,606
Effect of exchange rate changes on cash
Changes in cash, cash equivalents and restricted cash and cash equivalents
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year
Cash, cash equivalents and restricted cash and cash equivalents at end of year