Borrowings - Principal Payments (Table) (Details) - USD ($) $ in Thousands |
Sep. 30, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|---|
| BORROWINGS [Abstract] | |||
| September 30, 2019 | $ 34,840 | ||
| September 30, 2020 | 73,216 | ||
| September 30, 2021 | 56,817 | ||
| September 30, 2022 | 1,426,583 | ||
| September 30, 2023 | 33,042 | ||
| September 30, 2024 and thereafter | 4,087 | ||
| Total | $ 1,628,585 | $ 1,717,768 | $ 1,675,415 |
| 2019 | 35,988 | ||
| 2020 | 33,326 | ||
| 2021 | 71,454 | ||
| 2022 | 154,825 | ||
| 2023 | 1,414,638 | ||
| 2024 and thereafter | $ 7,537 |