Note 16 - Guarantor Subsidiaries - Unaudited Interim Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities	$ 120,866	$ 94,221	$ 115,878
Additions to properties, plants, and equipment	(121,421)	(136,933)	(98,038)
Other investing activities, net	1,554	39,712	1,475
Dividends paid to stockholders	(5,466)	(4,945)	(4,528)
Borrowings under debt arrangements	279,500	102,024	0
Repayments of debt	(286,657)	(113,375)	(6,986)
Other financing activity	45,812	1,412	6,266
Effect of exchange rate changes on cash	875	(1,515)	1,095
Changes in cash, cash equivalents and restricted cash and cash equivalents	35,063	(158,725)	15,162
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	28,414	187,139	171,977
Cash, cash equivalents and restricted cash and cash equivalents at end of year	63,477	28,414	187,139
Purchase of other companies, net of cash and restricted cash acquired	0	(139,326)	0
Reportable Legal Entities [Member] | Parent Company [Member]
Cash flows from operating activities	(162,380)	(222)	(139,900)
Additions to properties, plants, and equipment	0
Other investing activities, net	(58,933)	(209,525)	154,723
Dividends paid to stockholders	(5,466)	(4,945)	(4,528)
Borrowings under debt arrangements	279,500	102,024
Repayments of debt	(279,500)	(106,036)
Other financing activity	254,263	260,418	(19,692)
Effect of exchange rate changes on cash	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	27,484	(97,612)	(9,397)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	6,266	103,878	113,275
Cash, cash equivalents and restricted cash and cash equivalents at end of year	33,750	6,266	103,878
Purchase of other companies, net of cash and restricted cash acquired		(139,326)
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Cash flows from operating activities	158,854	91,999	(43,279)
Additions to properties, plants, and equipment	(116,386)	(130,110)	(85,534)
Other investing activities, net	139	6,789	7,901
Dividends paid to stockholders	0
Borrowings under debt arrangements	0
Repayments of debt	(7,157)	(7,339)	(6,986)
Other financing activity	(38,201)	11,816	134,178
Effect of exchange rate changes on cash	875	(1,515)	1,095
Changes in cash, cash equivalents and restricted cash and cash equivalents	(1,876)	(28,360)	7,375
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	18,258	46,618	39,243
Cash, cash equivalents and restricted cash and cash equivalents at end of year	16,382	18,258	46,618
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities	17,183	296,081	65,260
Additions to properties, plants, and equipment	(5,035)	(6,823)	(12,504)
Other investing activities, net	1,415		218
Dividends paid to stockholders	0
Borrowings under debt arrangements	0
Other financing activity	(4,108)	(322,011)	(35,790)
Effect of exchange rate changes on cash	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	9,455	(32,753)	17,184
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	3,890	36,643	19,459
Cash, cash equivalents and restricted cash and cash equivalents at end of year	13,345	3,890	36,643
Consolidation, Eliminations [Member]
Cash flows from operating activities	107,209	(293,637)	233,797
Additions to properties, plants, and equipment	0
Other investing activities, net	58,933	242,448	(161,367)
Dividends paid to stockholders	0
Borrowings under debt arrangements	0
Other financing activity	(166,142)	51,189	$ (72,430)
Effect of exchange rate changes on cash	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	0
Cash, cash equivalents and restricted cash and cash equivalents at beginning of year	0
Cash, cash equivalents and restricted cash and cash equivalents at end of year	$ 0	$ 0