Note 9 - Business Segments - Reconciling Information Between Reportable Segments and Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Revenue	$ 146,901	$ 174,900	$ 313,253	$ 367,013
Operating income (loss)	28,619	48,075	78,508	109,132
Interest income	808	441	1,071	843
Interest expense, net	(18,626)	(19,785)	(37,642)	(37,058)
Derivatives and foreign currency transaction gains (losses)	658	671	(16,208)	1,064
Income attributable to sale of tax benefits	7,420	5,672	13,775	9,804
Other non-operating income (expense), net	(21)	304	(352)	382
Total consolidated income before income taxes and equity in income of investees	18,858	35,378	39,152	84,167
Intersegment Eliminations [Member]
Revenue	51,038	50,453	76,372	59,109
Consolidation, Eliminations [Member]
Revenue	$ (51,038)	$ (50,453)	$ (76,372)	$ (59,109)