v3.26.1
Share-Based Compensation (Details) - USD ($)
$ / shares in Units, $ in Millions
 12 Months Ended
Mar. 31, 2026
Mar. 31, 2025
Mar. 31, 2024
Weighted-average assumptions used for options granted:      
Risk-free interest rate 4.02% 4.21% 3.59%
Expected life of options 6 years 1 month 6 days 6 years 1 month 6 days 6 years
Exptected dividend yield of stock 1.12% 0.94% 1.08%
Expected volatility of stock 28.16% 28.42% 27.92%
Summary of share option activity:      
Number of Options, Outstanding, Beginning of Period 1,823,883    
Weighted Average Exercise Price, Outstanding, Beginning of Period $ 185.51    
Number of Options, Granted 187,058    
Weighted Average Exercise Price, Granted $ 265.21    
Number of Options, Exercised (287,514)    
Weighted Average Exercise Price, Exercised $ 123.46    
Number of Options, Forfeited (6,560)    
Weighted Average Exercise Price, Forfeited $ 245.47    
Number of Options, Outstanding, End of Period 1,716,867 1,823,883  
Weighted Average Exercise Price, Outstanding, End of Period $ 204.51 $ 185.51  
Average Remaining Contractual Term, Outstanding 5 years 8 months 12 days    
Aggregate Intrinsic Value, Outstanding $ 49.7    
Number of Options, Exercisable 1,223,025    
Weighted Average Exercise Price, Exercisable $ 186.44    
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term 4 years 8 months 12 days    
Aggregate Intrinsic Value, Exercisable $ 49.6    
Summary of non-vested restricted share activity:      
Number of Restricted Shares, Non-vested at Beginning of Period 29,555    
Number of Restricted Shares, Granted 17,298    
Number of Restricted Shares, Vested (2,644)    
Number of Restricted Shares, Canceled (13,920)    
Number of Restricted Shares, Non-vested at End of Period 30,289 29,555  
Restricted Stock      
Summary of non-vested restricted share activity:      
Number of Restricted Shares, Non-vested at Beginning of Period 449,131    
Weighted-Average Grant Date Fair Value, Non-vested at Beginning of Period $ 214.21    
Number of Restricted Shares, Granted 167,055    
Weighted-Average Grant Date Fair Value, Granted $ 241.42    
Number of Restricted Shares, Vested (137,143)    
Weighted-Average Grant Date Fair Value, Vested $ 207.10    
Number of Restricted Shares, Canceled (22,963)    
Weighted-Average Grant Date Fair Value, Canceled $ 220.81    
Number of Restricted Shares, Non-vested at End of Period 456,080 449,131  
Weighted-Average Grant Date Fair Value, Non-vested at End of Period $ 226.73 $ 214.21