v3.25.4
Shareholders' equity - Capital stock (Details) - € / shares
12 Months Ended
Dec. 31, 2025
Jan. 16, 2026
Aug. 19, 2025
Jul. 03, 2025
Apr. 14, 2025
Mar. 04, 2025
Feb. 24, 2025
Jan. 03, 2025
Dec. 31, 2024
Feb. 13, 2024
Oct. 24, 2022
Shareholders' equity                      
Number of shares issued 293,413,449               293,413,449    
Nominal value per share € 1               € 1    
Vote to create Authorized Capital (as a percent) 75.00%                    
Period that management board may issue new shares 5 years                    
Maximum increase in Authorized Capital, as a percent to issued capital 50.00%                    
Vote to create Conditional Capital (as a percent) 75.00%                    
Maximum Conditional Capital, as a percent to issued capital 60.00%                    
Maximum Conditional Capital for purpose of issuing new shares to holders of convertible bonds or other securities which grant a right to shares, as percent to issued capital 50.00%                    
Maximum Conditional Capital for purpose of issuing shares to management and employees, as a percent to issued capital 20.00%                    
Fresenius SE                      
Shareholders' equity                      
Voting interest held (as a percent) 27.80%                    
Else Kroner-Fresenius-Stiftung                      
Shareholders' equity                      
Voting interest held (as a percent)           28.55%          
BlackRock, Inc.                      
Shareholders' equity                      
Voting interest held (as a percent)   4.74%                  
Voting interest held through instruments (as a percent)   0.34%                  
Artisan Partners Asset Management Inc.                      
Shareholders' equity                      
Voting interest held (as a percent)     2.99%                
Dodge & Cox International, San Francisco                      
Shareholders' equity                      
Voting interest held (as a percent)       4.98%              
Voting interest held through instruments (as a percent)                   7.40%  
Harris Associates L.P.                      
Shareholders' equity                      
Voting interest held (as a percent)         2.98%            
Dodge & Cox International Stock Fund                      
Shareholders' equity                      
Voting interest held (as a percent)             5.00%        
Harris Associates Investment Trust                      
Shareholders' equity                      
Voting interest held (as a percent)               3.00%      
Richard Pzena                      
Shareholders' equity                      
Voting interest held (as a percent)                     5.20%