Annual report pursuant to Section 13 and 15(d)

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

v3.22.2
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
May 31, 2022
May 31, 2021
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses $ (116.2) $ (4.0)
Securities in an unrealized loss position for less than twelve months, Fair value 2,059.6 419.9
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (22.8)  
Securities in an unrealized loss position for more than twelve months, Fair value 200.7  
Total, Gross unrealized losses (139.0) (4.0)
Total, Fair value 2,260.3 419.9
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses (0.9)  
Securities in an unrealized loss position for less than twelve months, Fair value 48.5 7.1
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.3)  
Securities in an unrealized loss position for more than twelve months, Fair value 5.7  
Total, Gross unrealized losses (1.2)  
Total, Fair value 54.2 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 (17.5) (0.2)
Securities in an unrealized loss position for less than twelve months, Fair value 425.4 22.0
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (1.5)  
Securities in an unrealized loss position for more than twelve months, Fair value 16.7  
Total, Gross unrealized losses (19.0) (0.2)
Total, Fair value 442.1 22.0
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 (81.9) (2.3)
Securities in an unrealized loss position for less than twelve months, Fair value 1,171.5 288.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (10.6)  
Securities in an unrealized loss position for more than twelve months, Fair value 86.6  
Total, Gross unrealized losses (92.5) (2.3)
Total, Fair value 1,258.1 288.2
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 (15.9) (1.5)
Securities in an unrealized loss position for less than twelve months, Fair value 414.2 102.6
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (10.4)  
Securities in an unrealized loss position for more than twelve months, Fair value 91.7  
Total, Gross unrealized losses (26.3) (1.5)
Total, Fair value $ 505.9 $ 102.6