Note 11 - Segment Reporting - Revenue to External Customers and Long-lived Assets by Geography (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues	$ 88,105	$ 78,173	$ 250,312	$ 225,702
Operating Segments [Member] | United States Segment [Member]
Revenues	67,490	59,574	191,019	169,364
Operating Segments [Member] | Europe Segment [Member]
Revenues	18,094	15,610	51,224	48,518
Operating Segments [Member] | Japan Segment [Member]
Revenues	$ 2,521	$ 2,989	$ 8,069	$ 7,820