Share Based Compensation - Dividend Payments (Details) - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2018 |
Dec. 31, 2017 |
|
| Stock Options and Restricted Shares | ||
| Share Based Compensation | ||
| Amount of cash bonuses and distributions related to all dividends previously declared | $ 2.0 | $ 2.0 |