Note 9 - Accumulated Other Comprehensive Loss - Other Comprehensive Loss (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Balance beginning of period			$ 379,833
Balance at end of period	$ 410,804		410,804
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance beginning of period	(9,568)	$ (4,468)	(10,753)	$ (5,212)
Other comprehensive income (loss) before reclassifications	2,164	(2,144)	3,349	(1,400)
Amounts reclassified from accumulated other comprehensive income	0	0	0	0
Net current-period other comprehensive income (loss)	2,164	(2,144)	3,349	(1,400)
Balance at end of period	$ (7,404)	$ (6,612)	$ (7,404)	$ (6,612)