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Financial Instruments - Financial Risk (Details) | 6 Months Ended | 12 Months Ended | 18 Months Ended
--- | --- | --- | ---
Jun. 30, 2021 | Dec. 31, 2020 | Jun. 30, 2021
Credit risk | Triple A-rating from Moody's, S&P or Fitch |  |  |
Disclosure of credit risk exposure [line items] |  |  |
Marketable securities were invested (as a percent) |  |  | 99.00%
Currency risk | EUR |  |  |
Disclosure of credit risk exposure [line items] |  |  |
Marketable securities were invested (as a percent) | 10.00% | 10.00% |
Currency risk | DKK |  |  |
Disclosure of credit risk exposure [line items] |  |  |
Marketable securities were invested (as a percent) | 20.00% | 19.00% |
Currency risk | USD |  |  |
Disclosure of credit risk exposure [line items] |  |  |
Marketable securities were invested (as a percent) | 69.00% | 70.00% |
Currency risk | GBP |  |  |
Disclosure of credit risk exposure [line items] |  |  |
Marketable securities were invested (as a percent) | 1.00% | 1.00% |

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