Other comprehensive income - Narrative (Details) - EUR (€) € in Millions	12 Months Ended
Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disclosure of analysis of other comprehensive income by item [line items]
Actuarial gains and losses on defined benefit pension plans	€ 73	€ 584	€ 1,038
Changes in value recognised in equity	220	643	944
Decrease due to other modification	147
Foreign exchange gain (loss)	407	(216)	(22)
Impairment loss (reversal)	12,546	12,136	12,298
Exchange differences	(25,475)	(22,375)	(19,510)
Equity Investments
Disclosure of analysis of other comprehensive income by item [line items]
Exchange differences	394	428	318
Reclassification adjustments on exchange differences on translation of foreign operations, net of tax	17	45	44
Financial assets at fair value through other comprehensive income
Disclosure of analysis of other comprehensive income by item [line items]
Impairment loss (reversal)	29	(1)	24
Goodwill
Disclosure of analysis of other comprehensive income by item [line items]
Foreign exchange gain (loss)	(287)	(568)	249
United Kingdom
Disclosure of analysis of other comprehensive income by item [line items]
Actuarial gains and losses on defined benefit pension plans	(117)	€ (475)	€ (687)
Decrease (increase) in accumulated actuarial losses/profits	€ 117
Annual discount rate	5.58%	5.54%	4.63%
Other material actuarial assumptions	2.90%	3.11%
Annual social security pension increase rate	2.78%	3.04%	2.96%
Brazil
Disclosure of analysis of other comprehensive income by item [line items]
Decrease (increase) in accumulated actuarial losses/profits	€ 116
Annual social security pension increase rate	10.65%	10.58%
Actuarial assumption of medical cost trend rates	10.52%	10.50%
Spain
Disclosure of analysis of other comprehensive income by item [line items]
Actuarial gains and losses on defined benefit pension plans	€ 33	€ (21)	€ (10)
Decrease (increase) in accumulated actuarial losses/profits	€ (33)
Annual discount rate	3.75%	3.00%
Other Regions
Disclosure of analysis of other comprehensive income by item [line items]
Decrease (increase) in accumulated actuarial losses/profits	€ 20

The discount rate used as the significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [domain]]

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The expected rate of increases in pension that is used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit plans [domain]; Defined benefit obligation, at present value; Actuarial assumptions [domain]]

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Medical cost trend rate used as significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Defined benefit obligation, at present value; Actuarial assumptions [domain]]

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The decrease (increase) in a net defined benefit liability (asset) resulting from actuarial gains (losses) arising from changes in financial assumptions that result in remeasurements of the net defined benefit liability (asset). Financial assumptions deal with items such as: (a) the discount rate; (b) benefit levels, excluding any cost of the benefits to be met by employees, and future salary; (c) in the case of medical benefits, future medical costs, including claim handling costs (ie the costs that will be incurred in processing and resolving claims, including legal and adjuster's fees); and (d) taxes payable by the plan on contributions relating to service before the reporting date or on benefits resulting from that service. [Refer: Net defined benefit liability (asset)]

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The amount of exchange differences recognised in profit or loss that arise from foreign currency transactions, excluding those arising on financial instruments measured at fair value through profit or loss in accordance with IFRS 9. [Refer: At fair value [member]; Classes of financial instruments [domain]]

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The amount of impairment loss, impairment gain or reversal of impairment loss that is recognised in profit or loss in accordance with paragraph 5.5.8 of IFRS 9 and that arises from applying the impairment requirements in Section 5.5 of IFRS 9.

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The increase (decrease) in the net defined benefit liability (asset) resulting from miscellaneous other changes. [Refer: Net defined benefit liability (asset); Increase (decrease) in net defined benefit liability (asset) resulting from expense (income) in profit or loss; Decrease (increase) in net defined benefit liability (asset) resulting from gain (loss) on remeasurement in other comprehensive income]

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The amount of other comprehensive income, before tax, related to gains (losses) on remeasurements of defined benefit plans, which comprise actuarial gains and losses; the return on plan assets, excluding amounts included in net interest on the net defined benefit liability (asset); and any change in the effect of the asset ceiling, excluding amounts included in net interest on the net defined benefit liability (asset). [Refer: Other comprehensive income; Defined benefit plans [domain]; Plan assets [member]; Net defined benefit liability (asset)] [Contrast: Decrease (increase) in net defined benefit liability (asset) resulting from gain (loss) on remeasurement in other comprehensive income]

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Any other material assumption used as a significant actuarial assumption to determine the present value of a defined benefit obligation. [Refer: Actuarial assumptions [domain]; Defined benefit obligation, at present value]

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The amount of reclassification adjustments related to exchange differences when the financial statements of foreign operations are translated, net of tax. Reclassification adjustments are amounts reclassified to profit (loss) in the current period that were recognised in other comprehensive income in the current or previous periods. [Refer: Other comprehensive income]

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A component of equity representing exchange differences on translation of financial statements recognised in other comprehensive income and accumulated in equity. [Refer: Other comprehensive income]

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