Note 9 - Business Segments - Reconciling Information Between Reportable Segments and Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Revenues	$ 179,364	$ 159,861	$ 369,262	$ 311,455
Operating income	53,152	51,887	112,648	102,430
Interest income	362	245	606	565
Interest expense, net	(14,540)	(18,401)	(29,463)	(34,424)
Derivatives and foreign currency transaction gains (losses)	1,703	(4,332)	3,041	(2,370)
Income attributable to sale of tax benefits	4,356	4,519	10,513	8,917
Other non-operating income (expense), net	6	49	(86)	240
Total consolidated income before income taxes and equity in income of investees	45,039	33,967	97,259	75,358
Intersegment Eliminations [Member]
Revenues	16,565	19,266	32,778	21,206
Consolidation, Eliminations [Member]
Revenues	$ (16,565)	$ (19,266)	$ (32,778)	$ (21,206)