v3.26.1
Funds Held for Clients and Corporate Investments (Amortized Cost and Fair Value of Available-for-Sale Securities by Contractual Maturity) (Details) - USD ($)
$ in Millions
May 31, 2026
May 31, 2025
Funds Held for Clients and Corporate Investments [Abstract]    
Due in one year or less, Amortized cost $ 912.6  
Due after one year through three years, Amortized cost 1,426.5  
Due after three years through five years, Amortized cost 599.1  
Due after five years, Amortized cost 1,602.7  
AFS securities, Amortized cost 4,540.9 $ 3,809.1
Due in one year or less, Fair value 906.9  
Due after one year through three years, Fair value 1,407.7  
Due after three years through five years, Fair value 595.8  
Due after five years, Fair value 1,578.0  
AFS securities, Fair value $ 4,488.4 $ 3,755.5