Corporate debt, Movement in corporate debt, split between cash and non-cash items (Details) - USD ($) $ in Thousands |
12 Months Ended | |
|---|---|---|
Dec. 31, 2020 |
Dec. 31, 2019 |
|
| Corporate debt [Abstract] | ||
| Initial balance | $ 723,791 | $ 684,073 |
| Cash flow | 171,182 | 6,620 |
| Non-cash changes | 98,752 | 33,098 |
| Final balance | $ 993,725 | $ 723,791 |