Note 10 - Segment Reporting - Revenue by Country (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Revenues from external customers	$ 22,811	$ 23,127	$ 45,821	$ 45,093
Revenues, percent	100.00%	100.00%	100.00%	100.00%
UNITED STATES
Revenues from external customers	$ 13,442	$ 15,269	$ 27,770	$ 29,076
Revenues, percent	59.00%	66.00%	60.00%	64.00%
UNITED KINGDOM
Revenues from external customers	$ 4,212	$ 2,034	$ 7,670	$ 5,394
Revenues, percent	18.00%	9.00%	17.00%	12.00%
All Others [Member]
Revenues from external customers	$ 5,157	$ 5,824	$ 10,381	$ 10,623
Revenues, percent	23.00%	25.00%	23.00%	24.00%