Note 9 - Business Segments - Reconciling Information Between Reportable Segments and Consolidated Totals (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Total Segment Revenues [Member]
Revenues:
Revenue	$ 159,861	$ 140,487	$ 311,455	$ 260,718
Intersegment Eliminations [Member]
Revenues:
Revenue	19,266	10,900	21,206	30,657
Consolidation, Eliminations [Member]
Revenues:
Revenue	(19,266)	(10,900)	(21,206)	(30,657)
Revenue	159,861	140,487	311,455	260,718
Operating income:
Operating income	51,887	38,643	102,430	68,494
Interest income	245	44	565	53
Interest expense, net	(18,401)	(18,859)	(34,424)	(36,687)
Derivatives and foreign currency transaction gains (losses)	(4,332)	(571)	(2,370)	(1,937)
Income attributable to sale of tax benefits	4,519	4,731	8,917	10,283
Other non-operating income (expense), net	49	(1,675)	240	(1,392)
Total consolidated income before income taxes and equity in income of investees	$ 33,967	$ 22,313	$ 75,358	$ 38,814