Note 18 - Accumulated Other Comprehensive Income (Loss) - Changes in Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Balance	$ 431,116	$ 368,516
Balance	522,007	431,116
Accumulated Net Investment Gain (Loss) Attributable to Parent [Member]
Balance	(1,023)	(375)
Other comprehensive loss before reclassifications	(343)	(623)
Amounts reclassified from accumulated other comprehensive income (loss)	2	(25)
Net current period other comprehensive loss	(341)	(648)
Balance	(1,364)	(1,023)
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Balance	(3,192)	1,841
Other comprehensive loss before reclassifications	6,369	(5,033)
Amounts reclassified from accumulated other comprehensive income (loss)
Net current period other comprehensive loss	6,369	(5,033)
Balance	3,177	(3,192)
AOCI Attributable to Parent [Member]
Balance	(4,215)	1,466
Other comprehensive loss before reclassifications	6,026	(5,656)
Amounts reclassified from accumulated other comprehensive income (loss)	2	(25)
Net current period other comprehensive loss	6,028	(5,681)
Balance	$ 1,813	$ (4,215)