Note 10 - Segment Reporting - Revenue by Country (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Revenues from external customers	$ 23,009	$ 21,966
Revenues, percent	100.00%	100.00%
UNITED STATES
Revenues from external customers	$ 14,328	$ 13,807
Revenues, percent	62.00%	63.00%
UNITED KINGDOM
Revenues from external customers	$ 3,458	$ 3,360
Revenues, percent	15.00%	15.00%
All Others [Member]
Revenues from external customers	$ 5,223	$ 4,799
Revenues, percent	23.00%	22.00%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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