Note 3 - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member]
Cash equivalents	$ 32,136	$ 39,233
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Government securities	19,486	25,232
Fair Value, Inputs, Level 1 [Member]
Total	51,622	64,465
Foreign currency forward contracts
Total
Fair Value, Inputs, Level 2 [Member] | Cash Equivalents [Member]
Cash equivalents
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Government securities
Fair Value, Inputs, Level 2 [Member]
Total
Foreign currency forward contracts	241	537
Total	241	537
Fair Value, Inputs, Level 3 [Member] | Cash Equivalents [Member]
Cash equivalents
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member]
Government securities
Fair Value, Inputs, Level 3 [Member]
Total
Foreign currency forward contracts
Total
Cash Equivalents [Member]
Cash equivalents	32,136	39,233
US Government Agencies Debt Securities [Member]
Government securities	19,486	25,232
Total	51,622	64,465
Foreign currency forward contracts	241	537
Total	$ 241	$ 537