Note 9 - Business Segments - Reconciling Information Between Reportable Segments and Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues	$ 157,185	$ 184,617	$ 526,447	$ 496,072
Operating income	43,970	48,223	156,618	150,653
Interest income	255	266	861	831
Interest expense, net	(11,692)	(17,137)	(41,155)	(51,561)
Derivatives and foreign currency transaction gains (losses)	(1,001)	(222)	2,040	(2,592)
Income attributable to sale of tax benefits	3,506	3,463	14,019	12,380
Other non-operating expense, net	(1,592)	(5,546)	(1,678)	(5,306)
Total consolidated income before income taxes and equity in losses of investees	33,446	29,047	130,705	104,405
Intersegment Eliminations [Member]
Revenues	28,248	14,835	61,026	36,042
Consolidation, Eliminations [Member]
Revenues	$ (28,248)	$ (14,835)	$ (61,026)	$ (36,042)