Project debt, Repayment schedule (Details) - USD ($) $ in Thousands |
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|---|
| Repayment schedule [Abstract] | |||
| Project debt | $ 5,091,114 | $ 5,475,208 | $ 5,330,467 |
| 2019 [Member] | |||
| Repayment schedule [Abstract] | |||
| Interest repayment | 21,916 | ||
| Nominal repayment | 242,538 | ||
| 2020 [Member] | |||
| Repayment schedule [Abstract] | |||
| Project debt | 257,012 | ||
| 2021 [Member] | |||
| Repayment schedule [Abstract] | |||
| Project debt | 268,625 | ||
| 2022 [Member] | |||
| Repayment schedule [Abstract] | |||
| Project debt | 299,840 | ||
| 2023 [Member] | |||
| Repayment schedule [Abstract] | |||
| Project debt | 326,413 | ||
| Subsequent Years [Member] | |||
| Repayment schedule [Abstract] | |||
| Project debt | $ 3,674,770 |