4. Income Taxes (Details 3) € in Thousands	Dec. 31, 2020 EUR (€)
United States
Net operating loss carry forwards	€ 76,987
United States | 2021
Net operating loss carry forwards	948
United States | 2022
Net operating loss carry forwards	1,775
United States | 2023
Net operating loss carry forwards	1,182
United States | 2024
Net operating loss carry forwards	1,226
United States | 2025
Net operating loss carry forwards	1,380
United States | 2026 - 2038
Net operating loss carry forwards	67,203
United States | Perpetual
Net operating loss carry forwards	3,273
Switzerland
Net operating loss carry forwards	63
Switzerland | 2021
Net operating loss carry forwards	0
Switzerland | 2022
Net operating loss carry forwards	0
Switzerland | 2023
Net operating loss carry forwards	0
Switzerland | 2024
Net operating loss carry forwards	63
Switzerland | 2025
Net operating loss carry forwards	0
Switzerland | 2026 - 2038
Net operating loss carry forwards	0
Switzerland | Perpetual
Net operating loss carry forwards	0
The Netherlands
Net operating loss carry forwards	5,289
The Netherlands | 2021
Net operating loss carry forwards	629
The Netherlands | 2022
Net operating loss carry forwards	0
The Netherlands | 2023
Net operating loss carry forwards	43
The Netherlands | 2024
Net operating loss carry forwards	0
The Netherlands | 2025
Net operating loss carry forwards	731
The Netherlands | 2026 - 2038
Net operating loss carry forwards	3,886
The Netherlands | Perpetual
Net operating loss carry forwards	€ 0