Quarterly report pursuant to Section 13 or 15(d)

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

v3.23.3
Funds Held for Clients and Corporate Investments (Narrative) (Details)
$ in Millions
3 Months Ended 12 Months Ended
Aug. 31, 2023
USD ($)
Security
May 31, 2023
USD ($)
Security
Schedule of Available-for-sale Securities [Line Items]    
Net unrealized losses on available-for-sale securities $ (206.9) $ (175.3)
Number of available-for-sale securities in an unrealized loss position | Security 1,027 967
Percentage of available-for-sale securities in an unrealized loss position 96.00% 88.00%
Gross unrealized losses on available-for-sale securities $ 207.7 $ 179.4
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross unrealized losses on available-for-sale securities $ 43.2 31.1
Corporate Bonds [Member] | Minimum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Sep. 01, 2023  
Corporate Bonds [Member] | Maximum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Aug. 16, 2029  
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Gross unrealized losses on available-for-sale securities $ 112.4 $ 105.3
Municipal Bonds [Member] | Minimum [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities maturity date Nov. 01, 2023  
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