Note 8 - Shareholders' Equity - Shareholders' Equity (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Balance, beginning of period			$ 52,201
Foreign currency translation adjustment	$ 9	$ (60)	(17)	$ (38)
Net loss	(2,098)	(2,163)	(4,447)	(4,009)
Balance, end of period	48,036	54,787	48,036	54,787
Common Stock Including Additional Paid in Capital [Member]
Balance, beginning of period	57,940	47,620	57,857	47,472
Share-based compensation expense	55	129	129	266
Proceeds from employee stock purchase plan	7	9	16	20
Balance, end of period	58,002	47,758	58,002	47,758
AOCI Attributable to Parent [Member]
Balance, beginning of period	(137)	(113)	(181)	(65)
Unrealized gain (loss) on available-for-sale securities, net of tax	84	(1)	154	(71)
Foreign currency translation adjustment	9	(60)	(17)	(38)
Balance, end of period	(44)	(174)	(44)	(174)
Retained Earnings [Member]
Balance, beginning of period	(7,824)	9,367	(5,475)	9,160
Stock repurchased				(147)
Cash dividends, $0.07 per share				(583)
Impact on retained earnings for change in revenue recognition policy				2,782
Net loss	(2,098)	(2,164)	(4,447)	(4,009)
Balance, end of period	$ (9,922)	$ 7,203	$ (9,922)	$ 7,203