Note 3 - Fair Value Measurements - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Inputs, Level 1 [Member] | Cash Equivalents [Member]
Cash equivalents	$ 18,118	$ 39,233
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Government securities	20,296	25,232
Fair Value, Inputs, Level 1 [Member]
Total	38,414	64,465
Forward foreign currency 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
Forward foreign currency contracts	98	537
Total	98	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
Forward foreign currency contracts
Total
Cash Equivalents [Member]
Cash equivalents	18,118	39,233
US Government Agencies Debt Securities [Member]
Government securities	20,296	25,232
Total	38,414	64,465
Forward foreign currency contracts	98	537
Total	$ 98	$ 537