Note K - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Stock based compensation expense | $ 6,600 | $ 2,369 | $ 214 |
| Research and Development Expense [Member] | |||
| Stock based compensation expense | 1,051 | 610 | 62 |
| General and Administrative Expense [Member] | |||
| Stock based compensation expense | 3,639 | 1,759 | 152 |
| Severance Expense [Member] | |||
| Stock based compensation expense | $ 1,910 | ||