Stock-Based Compensation (Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs) (Details) - USD ($) $ in Thousands |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2015 |
Dec. 31, 2014 |
Dec. 31, 2013 |
|
| Stock-based compensation expense by condensed consolidated statement of operations and comprehensive loss line item | |||
| Total expense | $ 1,751 | $ 1,839 | $ 1,721 |
| Research and development | |||
| Stock-based compensation expense by condensed consolidated statement of operations and comprehensive loss line item | |||
| Total expense | 364 | 271 | 1,120 |
| General and administrative | |||
| Stock-based compensation expense by condensed consolidated statement of operations and comprehensive loss line item | |||
| Total expense | $ 1,387 | $ 1,568 | $ 601 |