Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|
| Research and Development [Member] | |||
| Stock compensation expense | $ 1,192 | $ 1,277 | $ 1,158 |
| General and Administrative [Member] | |||
| Stock compensation expense | $ 1,676 | $ 1,652 | $ 1,447 |