Note 6 - Goodwill and Acquisition-related Intangible Assets, Net (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Goodwill, Period Increase (Decrease), Total	$ 0	$ 0
Amortization of Intangible Assets, Total	800	2,100	$ 2,100
Intangible Assets, Net (Excluding Goodwill), Total	$ 111	$ 951