v3.26.1
Provisions - Provisions Narrative (Details)
€ in Millions
 12 Months Ended
Dec. 31, 2025
EUR (€)
people
Dec. 31, 2024
EUR (€)
people
Dec. 31, 2023
EUR (€)
people
Disclosure of other provisions [line items]      
Number of employees accepted the pre-retirement and voluntary redundancy offers | people 1,238 826 502
Provisions recognized to cover expenses of pre-retirement and voluntary redundancy offers € 389 € 303 € 160
Contributions to defined contribution pension funds 332 354 307
Actuarial gains and losses on defined benefit pension plans (73) (584) (1,038)
Spain      
Disclosure of other provisions [line items]      
Contributions to defined contribution pension funds 130 126 116
Actuarial gains and losses on defined benefit pension plans € (33) € 21 € 10
Annual discount rate 3.75% 3.00%  
Spain | Post-employment plans      
Disclosure of other provisions [line items]      
Annual discount rate 3.75% 3.00% 3.35%
Cumulative annual CPI growth 2.00% 2.00% 2.00%
Spain | Other long term employee benefits      
Disclosure of other provisions [line items]      
Annual discount rate 3.75% 3.00% 3.35%
Cumulative annual CPI growth 2.00% 2.00% 2.00%
Spain | Discount rate actuarial assumptions      
Disclosure of other provisions [line items]      
Percentage of reasonably possible increase in actuarial assumption 0.50%    
Percentage of reasonably possible decrease in actuarial assumption 0.50%    
Spain | Discount rate actuarial assumptions | Post-employment plans      
Disclosure of other provisions [line items]      
Increase or decrease on obligations if decrease in actuarial assumption (as a percent) 4.02%    
Increase or decrease on obligations if increase in actuarial assumption (as a percent) (3.75%)    
Spain | Discount rate actuarial assumptions | Other long term employee benefits      
Disclosure of other provisions [line items]      
Increase or decrease on obligations if decrease in actuarial assumption (as a percent) 1.15%    
Increase or decrease on obligations if increase in actuarial assumption (as a percent) (1.15%)    
United Kingdom      
Disclosure of other provisions [line items]      
Contributions to defined contribution pension funds € 92 € 98 € 87
Actuarial gains and losses on defined benefit pension plans € 117 € 475 € 687
Annual discount rate 5.58% 5.54% 4.63%
Cumulative annual CPI growth 2.90% 3.11% 3.02%
United Kingdom | Discount rate actuarial assumptions      
Disclosure of other provisions [line items]      
Percentage of reasonably possible increase in actuarial assumption 0.50%    
Percentage of reasonably possible decrease in actuarial assumption 0.50%    
Increase or decrease on obligations if decrease in actuarial assumption (as a percent) 5.82%    
Increase or decrease on obligations if increase in actuarial assumption (as a percent) (5.28%)    
United Kingdom | Inflation rate assumption      
Disclosure of other provisions [line items]      
Percentage of reasonably possible increase in actuarial assumption 0.50%    
Percentage of reasonably possible decrease in actuarial assumption 0.50%    
Increase or decrease on obligations if decrease in actuarial assumption (as a percent) (4.14%)    
Increase or decrease on obligations if increase in actuarial assumption (as a percent) 4.23%    
Other foreign subsidiaries      
Disclosure of other provisions [line items]      
Contributions to defined contribution pension funds € 110 € 133 € 107
Actuarial gains and losses on defined benefit pension plans € 136 € 147 € 247
Other foreign subsidiaries | Discount rate actuarial assumptions      
Disclosure of other provisions [line items]      
Percentage of reasonably possible increase in actuarial assumption 0.50%    
Percentage of reasonably possible decrease in actuarial assumption 0.50%    
Increase or decrease on obligations if decrease in actuarial assumption (as a percent) 3.92%    
Increase or decrease on obligations if increase in actuarial assumption (as a percent) (3.53%)    
Brazil      
Disclosure of other provisions [line items]      
Cumulative annual CPI growth 3.00%    
Brazil | Minimum      
Disclosure of other provisions [line items]      
Annual discount rate 10.52%    
Brazil | Maximum      
Disclosure of other provisions [line items]      
Annual discount rate 10.65%    
Brazil | Provisions for employment-related proceedings (Brazil)      
Disclosure of other provisions [line items]      
Additional provisions charged to income statement € 524    
Provision used, other provisions 384    
Brazil | Legal proceedings provision      
Disclosure of other provisions [line items]      
Additional provisions charged to income statement 185    
Provision used, other provisions € 159