Note 14 - Accumulated Other Comprehensive Loss - Other Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Balance	$ 585,790	$ 541,497	$ 461,215
Balance	644,356	585,790	541,497
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(7,018)	(8,492)	(5,234)
Other comprehensive (loss) income before reclassifications	3,598	1,474	(3,258)
Amounts reclassified from accumulated other comprehensive income (loss)	0	0	0
Net current-period other comprehensive (loss) income	3,598	1,474	(3,258)
Balance	$ (3,420)	$ (7,018)	$ (8,492)