Note 5 - Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands |
Mar. 31, 2016 |
Dec. 31, 2015 |
---|---|---|
Money Market Funds [Member] | Fair Value, Inputs, Level 2 [Member] | ||
Cash equivalents | $ 66,449 | $ 61,385 |
Money Market Funds [Member] | ||
Cash equivalents | 66,449 | 61,385 |
Certificates of Deposit [Member] | Fair Value, Inputs, Level 2 [Member] | ||
Cash equivalents | 250 | |
Investments | 23,000 | 25,750 |
Certificates of Deposit [Member] | ||
Cash equivalents | 250 | |
Investments | 23,000 | 25,750 |
Corporate Debt Securities [Member] | ||
Investments | 2,001 | |
Fair Value, Inputs, Level 2 [Member] | ||
Cash equivalents | 61,635 | |
Cash equivalents | 61,635 | |
Investments | $ 23,000 | $ 27,751 |