Note 3 - Fair Value Measurement - Fair Value of Assets Measured on a Recurring Basis (Details) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands |
Sep. 30, 2018 |
Dec. 31, 2017 |
---|---|---|
Assets: | ||
Cash equivalents | $ 4,854 | $ 12,063 |
Fair Value, Inputs, Level 1 [Member] | ||
Assets: | ||
Cash equivalents | 4,854 | 12,063 |
Fair Value, Inputs, Level 2 [Member] | ||
Assets: | ||
Cash equivalents | ||
Fair Value, Inputs, Level 3 [Member] | ||
Assets: | ||
Cash equivalents |