Corporate debt, Breakdown of corporate debt (Details) - USD ($) $ in Thousands |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Corporate debt [Abstract] | ||
| Total Non-Current | $ 415,168 | $ 574,176 |
| Total Current | 268,905 | 68,907 |
| Credit Facilities with Financial Entities [Member] | ||
| Corporate debt [Abstract] | ||
| Total Non-Current | 415,168 | 320,783 |
| Total Current | 11,580 | 65,833 |
| Notes and Bonds [Member] | ||
| Corporate debt [Abstract] | ||
| Total Non-Current | 0 | 253,393 |
| Total Current | $ 257,325 | $ 3,074 |