Annual report pursuant to Section 13 and 15(d)

Funds Held for Clients and Corporate Investments (Narrative) (Details)

v3.24.2
Funds Held for Clients and Corporate Investments (Narrative) (Details)
$ in Millions
12 Months Ended
May 31, 2024
USD ($)
Security
May 31, 2023
USD ($)
Security
Schedule of Available-for-sale Securities [Line Items]    
Gross unrealized losses on available-for-sale securities $ 164.2 $ 179.4
Net unrealized losses on available-for-sale securities $ (162.5) $ (175.3)
Number of available-for-sale securities in an unrealized loss position | Security 957 967
Percentage of available-for-sale securities in an unrealized loss position 95.00% 88.00%
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross unrealized losses on available-for-sale securities $ 32.8 $ 31.1
Corporate Bonds [Member] | Minimum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Jun. 01, 2024  
Corporate Bonds [Member] | Maximum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Sep. 15, 2029  
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross unrealized losses on available-for-sale securities $ 86.9 $ 105.3
Municipal Bonds [Member] | Minimum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Jun. 01, 2024  
Municipal Bonds [Member] | Maximum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Oct. 01, 2031  
Variable Rate Demand Notes [Member] | Minimum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities contractual maturities 20 years  
Variable Rate Demand Notes [Member] | Maximum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities contractual maturities 30 years