Note K - Stock-based Compensation (Details Textual) - USD ($)
|
12 Months Ended |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period |
14,933
|
4,766
|
0
|
| Stock Issued During Period, Value, Stock Options Exercised |
$ 71,000
|
$ 28,000
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value |
$ 169,000
|
$ 54,000
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value |
$ 9.25
|
$ 10.63
|
$ 4.50
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value |
$ 5,400,000
|
$ 1,100,000
|
$ 200,000
|
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized |
$ 10,600,000
|
|
|
| Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition |
2 years 313 days
|
|
|
| Allocated Share-based Compensation Expense |
$ 6,600,000
|
$ 2,369,000
|
214,000
|
| Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested, Number of Shares |
13,333
|
163,998
|
|
| Research and Development Expense [Member] |
|
|
|
| Allocated Share-based Compensation Expense |
$ 1,051,000
|
$ 610,000
|
62,000
|
| General and Administrative Expense [Member] |
|
|
|
| Allocated Share-based Compensation Expense |
3,639,000
|
1,759,000
|
$ 152,000
|
| Performance Shares [Member] | Research and Development Expense [Member] |
|
|
|
| Allocated Share-based Compensation Expense |
$ 44,000
|
200,000
|
|
| Performance Shares [Member] | General and Administrative Expense [Member] |
|
|
|
| Allocated Share-based Compensation Expense |
|
$ 700,000
|
|
| 2014 Equity Incentive Plan [Member] |
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized |
2,846,304
|
|
|
| Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Reserved for Issuance, Incremental Percentage of Capital Stock Outstanding |
4.00%
|
|
|
| Increase in Common Stock Reserved for Issuance |
585,879
|
|
|