Borrowings - Principal Payments (Table) (Details) - USD ($) $ in Thousands |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| BORROWINGS [Abstract] | ||
| 2018 | $ 35,988 | |
| 2019 | 33,326 | |
| 2020 | 71,454 | |
| 2021 | 154,825 | |
| 2022 | 1,414,638 | |
| 2023 and thereafter | 7,537 | |
| Total | $ 1,717,768 | $ 1,675,415 |