Goodwill and acquisitions (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	€ 500	€ 475	€ 479
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	25	(5)
Goodwill Extend		475
Construction division [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	140	135	132
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	5	3
Construction division [Member] \| Webber [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	69	65	67
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	4	(2)
Construction division [Member] \| Budimex S.A [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	71	70	65
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	1	5
Toll roads division [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	276	259	265
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	17	(6)
Toll roads division [Member] \| I66 Express mobility partners hold LLC [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	276	259	265
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	17	(6)
Airports division [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	27	27	27
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	0	0
Airports division [Member] \| Dalaman international airport [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	27	27	27
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	0	0
Energy and mobility infrastructures division [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	46	43	45
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	3	(1)
Energy and mobility infrastructures division [Member] \| Power transmission services chile [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	46	43	45
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	3	(1)
Energy and mobility infrastructures division [Member] \| Mining services Chile
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill		10	11
Increase (decrease) through other changes, goodwill		0
Increase (decrease) through net exchange differences, goodwill		(1)
Other division [Member]
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	10	10	€ 11
Increase (decrease) through other changes, goodwill	0	0
Increase (decrease) through net exchange differences, goodwill	(1)	(1)
Other division [Member] \| Mining services Chile
Disclosure of reconciliation of changes in goodwill [line items]
Goodwill	10	€ 10
Increase (decrease) through other changes, goodwill	0
Increase (decrease) through net exchange differences, goodwill	€ (1)

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The amount of assets representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognised. [Refer: Total for all business combinations [member]]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The increase (decrease) in goodwill resulting from net exchange differences arising on the translation of the financial statements from the functional currency into a different presentation currency, including the translation of a foreign operation into the presentation currency of the reporting entity. [Refer: Goodwill]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The increase (decrease) in goodwill resulting from changes that the entity does not separately disclose in the same statement or note. [Refer: Goodwill]

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