Note 14 - Guarantor Subsidiaries - Unaudited Interim Condensed Consolidating Statements of Cash Flows (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Cash flows from operating activities	$ 8,713	$ 47,018
Additions to properties, plants, and equipment	(71,245)	(43,304)
Other investing activities, net	(82)	28,117
Dividends paid to stockholders	(2,706)	(2,276)
Borrowings on debt	170,000	31,024
Payments on debt	(121,377)	(3,762)
Other financing activity	(1,690)	(2,697)
Effect of exchange rate changes on cash	432	(532)
Changes in cash, cash equivalents and restricted cash and cash equivalents	(17,955)	53,588
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	28,414	187,139
Cash, cash equivalents and restricted cash and cash equivalents at end of period	10,459	240,727
Reportable Legal Entities [Member] | Parent Company [Member]
Cash flows from operating activities	(168,393)	27,981
Additions to properties, plants, and equipment	0	0
Other investing activities, net	71,485	6,294
Dividends paid to stockholders	(2,706)	(2,276)
Borrowings on debt	170,000	31,024
Payments on debt	(118,000)	0
Other financing activity	41,363	(3,544)
Effect of exchange rate changes on cash	0	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	(6,251)	59,479
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	6,265	103,878
Cash, cash equivalents and restricted cash and cash equivalents at end of period	14	163,357
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Cash flows from operating activities	2,714	60,805
Additions to properties, plants, and equipment	(52,144)	(25,454)
Other investing activities, net	17	44
Dividends paid to stockholders	0	0
Borrowings on debt	0	0
Payments on debt	(2,475)	(1,393)
Other financing activity	20,906	(40,658)
Effect of exchange rate changes on cash	0	0
Changes in cash, cash equivalents and restricted cash and cash equivalents	(6,554)	(6,656)
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	9,686	32,048
Cash, cash equivalents and restricted cash and cash equivalents at end of period	3,132	25,392
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Cash flows from operating activities	12,414	2,166
Additions to properties, plants, and equipment	(19,101)	(17,850)
Other investing activities, net	(99)	420
Dividends paid to stockholders	0	0
Borrowings on debt	0	0
Payments on debt	(902)	(2,369)
Other financing activity	2,106	18,930
Effect of exchange rate changes on cash	432	(532)
Changes in cash, cash equivalents and restricted cash and cash equivalents	(5,150)	765
Cash, cash equivalents and restricted cash and cash equivalents at beginning of period	12,463	51,213
Cash, cash equivalents and restricted cash and cash equivalents at end of period	7,313	51,978
Consolidation, Eliminations [Member]
Cash flows from operating activities	137,550	(43,934)
Additions to properties, plants, and equipment		0
Other investing activities, net	(71,485)	21,359
Dividends paid to stockholders		0
Borrowings on debt		0
Payments on debt		0
Other financing activity	(66,065)	22,575
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
Cash, cash equivalents and restricted cash and cash equivalents at end of period	$ 0	$ 0