Note 2 - Summary of Significant Accounting Policies - Revenue By Country (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue, amount	$ 96,789	$ 83,275	$ 86,461
Revenue, percent	100.00%	100.00%	100.00%
UNITED STATES
Revenue, amount	$ 59,319	$ 50,875	$ 46,514
Revenue, percent	61.00%	61.00%	54.00%
UNITED KINGDOM
Revenue, amount	$ 15,185	$ 14,522	$ 17,337
Revenue, percent	16.00%	17.00%	20.00%
CHINA
Revenue, amount	$ 5,463	$ 5,381	$ 5,930
Revenue, percent	6.00%	7.00%	7.00%
All Others [Member]
Revenue, amount	$ 16,822	$ 12,497	$ 16,680
Revenue, percent	17.00%	15.00%	19.00%