Stock Option Based Compensation and Restricted Stock Compensation (Details Textual) - USD ($) |
3 Months Ended | 6 Months Ended | ||
|---|---|---|---|---|
Jun. 30, 2017 |
Jun. 30, 2016 |
Jun. 30, 2017 |
Jun. 30, 2016 |
|
| Share-based and Restricted Stock Compensation Expense [Abstract] | ||||
| Stock-based compensation expense included in operating expense | $ 2,735,000 | $ 2,977,000 | ||
| Restricted Stock [Member] | ||||
| Share-based and Restricted Stock Compensation Expense [Abstract] | ||||
| Stock-based compensation expense included in operating expense | $ 324,000 | $ 987,000 | 686,000 | 2,879,000 |
| Employee Stock Option [Member] | ||||
| Share-based and Restricted Stock Compensation Expense [Abstract] | ||||
| Stock-based compensation expense included in operating expense | $ 1,243,000 | $ 1,385,000 | $ 2,735,000 | $ 2,977,000 |
| Share-based Arrangements Awards Granted [Abstract] | ||||
| Stock options granted (in shares) | 185,000 | 125,000 | 185,000 | 1,440,000 |