v3.26.1
FAIR VALUE MEASUREMENTS - Plan's investments at fair value (Details) - North America 401(k) Savings Plan - USD ($)
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
FAIR VALUE MEASUREMENTS    
Investments $ 3,639,476,068 $ 3,176,427,504
Transfer among Level 1, 2 or 3 0  
Fair value hierarchy    
FAIR VALUE MEASUREMENTS    
Investments 445,655,359 141,882,201
Level 1    
FAIR VALUE MEASUREMENTS    
Investments 444,891,571 140,749,773
Level 2    
FAIR VALUE MEASUREMENTS    
Investments 763,788 1,132,428
Net Asset Value    
FAIR VALUE MEASUREMENTS    
Investments 3,193,820,709 3,034,545,303
Mutual Fund | Fair value hierarchy    
FAIR VALUE MEASUREMENTS    
Investments 305,689,698 30,397,222
Mutual Fund | Level 1    
FAIR VALUE MEASUREMENTS    
Investments 305,689,698 30,397,222
Fresenius Medical Care AG - Shares | Fair value hierarchy    
FAIR VALUE MEASUREMENTS    
Investments 14,236,904 15,861,109
Fresenius Medical Care AG - Shares | Level 1    
FAIR VALUE MEASUREMENTS    
Investments 14,236,904 15,861,109
Self-Directed Brokerage Accounts | Fair value hierarchy    
FAIR VALUE MEASUREMENTS    
Investments 107,822,211 78,422,707
Self-Directed Brokerage Accounts | Level 1    
FAIR VALUE MEASUREMENTS    
Investments 107,058,423 77,290,279
Self-Directed Brokerage Accounts | Level 2    
FAIR VALUE MEASUREMENTS    
Investments 763,788 1,132,428
Interest-Bearing Cash | Fair value hierarchy    
FAIR VALUE MEASUREMENTS    
Investments 17,906,546 17,201,163
Interest-Bearing Cash | Level 1    
FAIR VALUE MEASUREMENTS    
Investments $ 17,906,546 $ 17,201,163