Note 7 - Share Option and Equity Incentive Plan - Expense Recognized During the Year Related to Share-based Compensation Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Share-based compensation	$ 1,434	$ 1,355	$ 2,760	$ 2,459
Cost of Revenue [Member]
Share-based compensation	43	39	86	(13)
Research and Development Expense [Member]
Share-based compensation	171	107	331	232
Selling and Marketing Expense [Member]
Share-based compensation	445	469	870	895
General and Administrative Expense [Member]
Share-based compensation	$ 775	$ 740	$ 1,473	$ 1,345