Note 3 - Revenue - Total Revenue by Geographic Location (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Revenue	$ 26,787	$ 27,184	$ 78,599	$ 84,032
Percentage of Revenue	100.00%	100.00%	100.00%	100.00%
UNITED STATES
Revenue	$ 21,695	$ 22,227	$ 63,377	$ 68,624
Percentage of Revenue	81.00%	82.00%	81.00%	82.00%
Europe [Member]
Revenue	$ 3,132	$ 2,832	$ 9,021	$ 9,743
Percentage of Revenue	12.00%	10.00%	11.00%	11.00%
Other Location [Member]
Revenue	$ 1,960	$ 2,125	$ 6,201	$ 5,665
Percentage of Revenue	7.00%	8.00%	8.00%	7.00%