Equity Compensation (Fair Value) (Details) - Stock options - USD ($) $ in Thousands |
3 Months Ended | 6 Months Ended | |
|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2018 |
Jun. 30, 2017 |
|
| Stock options | |||
| Total fair value for the awards vested during the period | $ 500 | $ 1,200 | |
| Intrinsic-value | |||
| Options Exercised | 3,693 | $ 6,734 | |
| Options Exercisable | 19,801 | 19,801 | 19,345 |
| Options Vested and Expected to Vest | $ 21,492 | $ 21,492 | $ 21,817 |