Stock Option-Based Compensation and Restricted Stock Compensation (Details Textual) - USD ($) |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2017 |
Sep. 30, 2016 |
Sep. 30, 2017 |
Sep. 30, 2016 |
|
| Share-based and Restricted Stock Compensation Expense [Abstract] | ||||
| Stock-based compensation expense included in operating expense | $ 3,527,000 | $ 3,894,000 | ||
| Stock Options [Member] | ||||
| Share-based and Restricted Stock Compensation Expense [Abstract] | ||||
| Stock-based compensation expense included in operating expense | $ 792,000 | $ 917,000 | $ 3,527,000 | $ 3,894,000 |
| Share-based Arrangements Awards Granted [Abstract] | ||||
| Stock options granted (in shares) | 185,000 | 1,440,000 | 185,000 | 1,440,000 |
| Restricted Stock [Member] | ||||
| Share-based and Restricted Stock Compensation Expense [Abstract] | ||||
| Stock-based compensation expense included in operating expense | $ 293,000 | $ 241,000 | $ 979,000 | $ 3,120,000 |