Note 3 - Summary of Assets and Liabilities Measured at Fair Value (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Inputs, Level 1 [Member] | Cash and Cash Equivalents [Member]
Financial Assets	$ 39,233	$ 68,830
Fair Value, Inputs, Level 1 [Member] | US Government Agencies Debt Securities [Member]
Financial Assets	$ 25,232	$ 6,508
Fair Value, Inputs, Level 1 [Member] | Corporate Debt Securities [Member]
Financial Assets
Fair Value, Inputs, Level 1 [Member] | Foreign Currency Forward Contracts [Member]
Financial Liabilities
Fair Value, Inputs, Level 1 [Member]
Financial Assets	$ 64,465	$ 75,338
Financial Liabilities
Fair Value, Inputs, Level 2 [Member] | Cash and Cash Equivalents [Member]
Financial Assets
Fair Value, Inputs, Level 2 [Member] | US Government Agencies Debt Securities [Member]
Financial Assets
Fair Value, Inputs, Level 2 [Member] | Corporate Debt Securities [Member]
Financial Assets		$ 8,247
Fair Value, Inputs, Level 2 [Member] | Foreign Currency Forward Contracts [Member]
Financial Liabilities	$ 537
Fair Value, Inputs, Level 2 [Member]
Financial Assets		$ 8,247
Financial Liabilities	$ 537
Fair Value, Inputs, Level 3 [Member] | Cash and Cash Equivalents [Member]
Financial Assets
Fair Value, Inputs, Level 3 [Member] | US Government Agencies Debt Securities [Member]
Financial Assets
Fair Value, Inputs, Level 3 [Member] | Corporate Debt Securities [Member]
Financial Assets
Fair Value, Inputs, Level 3 [Member] | Foreign Currency Forward Contracts [Member]
Financial Liabilities
Fair Value, Inputs, Level 3 [Member]
Financial Assets
Financial Liabilities
Cash and Cash Equivalents [Member]
Financial Assets	$ 39,233	$ 68,830
US Government Agencies Debt Securities [Member]
Financial Assets	25,232	6,508
Corporate Debt Securities [Member]
Financial Assets		8,247
Foreign Currency Forward Contracts [Member]
Financial Liabilities	537
Financial Assets	64,465	$ 83,585
Financial Liabilities	$ 537