Summary of Significant Account Policies, Restricted Cash (Table) (Details) - USD ($) $ in Thousands |
Jun. 30, 2018 |
Dec. 31, 2017 |
Jun. 30, 2017 |
Dec. 31, 2016 |
|---|---|---|---|---|
| RESTRICTED CASH AND CASH EQUIVALENTS [ABSTRACT] | ||||
| Cash and cash equivalents | $ 118,454 | $ 127,632 | $ 130,208 | |
| Restricted cash | 2,978 | 6,558 | 4,462 | |
| Total cash and cash equivalents and restricted cash | $ 121,432 | $ 134,190 | $ 134,670 | $ 141,377 |