Quarterly report pursuant to Section 13 or 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
Aug. 31, 2021
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 $ (1.7) $ (4.0)
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.1)  
Total, Gross unrealized losses (1.8) (4.0)
Securities in an unrealized loss position for less than twelve months, Fair value 268.7 419.9
Securities in an unrealized loss position for more than twelve months, Fair value 5.2  
Total, Fair value 273.9 419.9
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Fair value 6.0 7.1
Total, Fair value 6.0 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) (0.2)
Total, Gross unrealized losses (0.2) (0.2)
Securities in an unrealized loss position for less than twelve months, Fair value 32.5 22.0
Total, Fair value 32.5 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 (0.7) (2.3)
Total, Gross unrealized losses (0.7) (2.3)
Securities in an unrealized loss position for less than twelve months, Fair value 126.5 288.2
Total, Fair value 126.5 288.2
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 (0.8) (1.5)
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.1)  
Total, Gross unrealized losses (0.9) (1.5)
Securities in an unrealized loss position for less than twelve months, Fair value 103.7 102.6
Securities in an unrealized loss position for more than twelve months, Fair value 5.2  
Total, Fair value $ 108.9 $ 102.6