Annual report pursuant to Section 13 and 15(d)

Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details)

v3.21.2
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
May 31, 2021
May 31, 2020
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses $ (4.0) $ (1.7)
Total, Gross unrealized losses (4.0) (1.7)
Securities in an unrealized loss position for less than twelve months, Fair value 419.9 66.8
Total, Fair value 419.9 66.8
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Fair value 7.1  
Total, Fair value 7.1  
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses (0.2) (0.1)
Total, Gross unrealized losses (0.2) (0.1)
Securities in an unrealized loss position for less than twelve months, Fair value 22.0 6.5
Total, Fair value 22.0 6.5
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses (2.3) (1.6)
Total, Gross unrealized losses (2.3) (1.6)
Securities in an unrealized loss position for less than twelve months, Fair value 288.2 60.3
Total, Fair value 288.2 $ 60.3
U.S. Government Agency And Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses (1.5)  
Total, Gross unrealized losses (1.5)  
Securities in an unrealized loss position for less than twelve months, Fair value 102.6  
Total, Fair value $ 102.6