Note 13 - Guarantor Subsidiaries - Unaudited Interim Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Cash flows from operating activities	$ 42,453	$ 8,713
Additions to properties, plants, and equipment	(30,689)	(71,245)
Other investing activities, net	(437)	(82)
Dividends paid to stockholders	(2,898)	(2,706)
Issuance of debt	679,500	170,000
Payments on debt	(669,340)	(121,377)
Other financing activity	(3,296)	(1,690)
Effect of exchange rate changes on cash	(1,794)	432
Changes in cash, cash equivalents and restricted cash and cash equivalents	13,499	(17,955)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	63,477	28,414
Cash, cash equivalents and restricted cash and cash equivalents at end of period	76,976	10,459
Reportable Legal Entities [Member] | Parent Company [Member]
Cash flows from operating activities	(8,252)	(168,393)
Additions to properties, plants, and equipment	0	0
Other investing activities, net	(6,728)	71,485
Dividends paid to stockholders	(2,898)	(2,706)
Issuance of debt	679,500	170,000
Payments on debt	(666,500)	(118,000)
Other financing activity	13,199	41,363
Effect of exchange rate changes on cash	0	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	8,321	(6,251)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	33,750	6,265
Cash, cash equivalents and restricted cash and cash equivalents at end of period	42,071	14
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Cash flows from operating activities	77,161	13,738
Additions to properties, plants, and equipment	(30,385)	(64,800)
Other investing activities, net	156	(82)
Dividends paid to stockholders	0	0
Issuance of debt	0	0
Payments on debt	(2,840)	2,858
Other financing activity	(34,040)	37,620
Effect of exchange rate changes on cash	(858)	432
Changes in cash, cash equivalents and restricted cash and cash equivalents	9,194	(10,234)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	16,382	18,259
Cash, cash equivalents and restricted cash and cash equivalents at end of period	25,576	8,025
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities	6,188	25,818
Additions to properties, plants, and equipment	(304)	(6,445)
Other investing activities, net	(593)	0
Dividends paid to stockholders	0	0
Issuance of debt	0	0
Payments on debt	0	(6,235)
Other financing activity	(8,371)	(14,608)
Effect of exchange rate changes on cash	(936)	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	(4,016)	(1,470)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	13,345	3,890
Cash, cash equivalents and restricted cash and cash equivalents at end of period	9,329	2,420
Consolidation, Eliminations [Member]
Cash flows from operating activities	(32,644)	137,550
Additions to properties, plants, and equipment	0
Other investing activities, net	6,728	(71,485)
Dividends paid to stockholders	0
Issuance of debt	0
Payments on debt	0
Other financing activity	25,916	(66,065)
Effect of exchange rate changes on cash	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	0	0
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	0	0
Cash, cash equivalents and restricted cash and cash equivalents at end of period	$ 0	$ 0