Significant accounting policies, Contracted Concessional Assets (Details) |
12 Months Ended |
|---|---|
Dec. 31, 2021 | |
| Spain [Member] | |
| Revenue Recognition [Abstract] | |
| Percentage of receiving a remuneration based on reasonable rate of return on assets | 7.09% |
| Other [Member] | |
| Revenue Recognition [Abstract] | |
| Percentage of receiving a remuneration based on reasonable rate of return on assets | 7.398% |