Investments (Details) - USD ($) $ in Thousands |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
Jun. 30, 2018 |
Jun. 30, 2017 |
Dec. 31, 2017 |
|
| Proceeds and realized gains and losses recognized | |||
| Sale Proceeds | $ 0 | $ 0 | |
| Available For Sale Securities | |||
| Investments | |||
| Cost | 595 | $ 595 | |
| Gross unrealized gains | 106 | 82 | |
| Available-for-sale securities, at fair value | $ 701 | $ 677 | |