Note 2 - Summary of Significant Accounting Policies - Revenue By Country (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue, amount	$ 23,492	$ 20,342	$ 18,843
Revenue Benchmark [Member] | Geographic Concentration Risk [Member]
Revenue, percent	100.00%	100.00%	100.00%
UNITED STATES
Revenue, amount	$ 9,654	$ 4,311	$ 3,158
UNITED STATES | Revenue Benchmark [Member] | Geographic Concentration Risk [Member]
Revenue, percent	41.00%	21.00%	17.00%
UNITED KINGDOM
Revenue, amount	$ 13,391	$ 15,118	$ 14,479
UNITED KINGDOM | Revenue Benchmark [Member] | Geographic Concentration Risk [Member]
Revenue, percent	57.00%	74.00%	77.00%
All Others [Member]
Revenue, amount	$ 447	$ 913	$ 1,206
All Others [Member] | Revenue Benchmark [Member] | Geographic Concentration Risk [Member]
Revenue, percent	2.00%	5.00%	6.00%