Capital Structure and Financial Risk and Related Items - Financial risk factors (Details)
$ in Thousands |
12 Months Ended |
|
Dec. 31, 2017
USD ($)
item
|
Dec. 31, 2016
USD ($)
item
|
Dec. 31, 2015
USD ($)
item
|
| Financial risk factors |
|
|
|
| Number of banks | item |
3
|
1
|
1
|
| Credit Risk |
|
|
|
| Financial risk factors |
|
|
|
| Cash and cash equivalents on deposit at the Bank |
$ 88,600
|
|
|
| USD | Foreign Currency |
|
|
|
| Financial risk factors |
|
|
|
| Possible change increase (as a percentage) |
10.00%
|
|
|
| Possible change decrease (as a percentage) |
(10.00%)
|
|
|
| Increase (decrease) to profit and loss due to increase in risk percentage |
$ 5,625
|
$ 7,124
|
$ 8,068
|
| Increase (decrease) to profit and loss due to decrease in risk percentage |
$ (5,625)
|
(7,124)
|
(8,068)
|
| GBP | Foreign Currency |
|
|
|
| Financial risk factors |
|
|
|
| Possible change increase (as a percentage) |
10.00%
|
|
|
| Possible change decrease (as a percentage) |
(10.00%)
|
|
|
| Increase (decrease) to profit and loss due to increase in risk percentage |
$ 128
|
430
|
1,001
|
| Increase (decrease) to profit and loss due to decrease in risk percentage |
$ (128)
|
(430)
|
(1,001)
|
| EUR | Foreign Currency |
|
|
|
| Financial risk factors |
|
|
|
| Possible change increase (as a percentage) |
2.00%
|
|
|
| Possible change decrease (as a percentage) |
(2.00%)
|
|
|
| Increase (decrease) to profit and loss due to increase in risk percentage |
$ 506
|
1,212
|
1,424
|
| Increase (decrease) to profit and loss due to decrease in risk percentage |
$ (506)
|
$ (1,212)
|
$ (1,424)
|