Quarterly report pursuant to Section 13 or 15(d)

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

v3.22.2.2
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
Aug. 31, 2022
May 31, 2022
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses $ (143.2) $ (116.2)
Securities in an unrealized loss position for less than twelve months, Fair value 2,430.4 2,059.6
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (32.4) (22.8)
Securities in an unrealized loss position for more than twelve months, Fair value 243.1 200.7
Total, Gross unrealized losses (175.6) (139.0)
Total, Fair value 2,673.5 2,260.3
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 (1.2) (0.9)
Securities in an unrealized loss position for less than twelve months, Fair value 48.8 48.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.4) (0.3)
Securities in an unrealized loss position for more than twelve months, Fair value 5.7 5.7
Total, Gross unrealized losses (1.6) (1.2)
Total, Fair value 54.5 54.2
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 (24.8) (17.5)
Securities in an unrealized loss position for less than twelve months, Fair value 634.3 425.4
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (3.5) (1.5)
Securities in an unrealized loss position for more than twelve months, Fair value 29.1 16.7
Total, Gross unrealized losses (28.3) (19.0)
Total, Fair value 663.4 442.1
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 (92.8) (81.9)
Securities in an unrealized loss position for less than twelve months, Fair value 1,279.2 1,171.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (15.5) (10.6)
Securities in an unrealized loss position for more than twelve months, Fair value 111.5 86.6
Total, Gross unrealized losses (108.3) (92.5)
Total, Fair value 1,390.7 1,258.1
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 (24.4) (15.9)
Securities in an unrealized loss position for less than twelve months, Fair value 468.1 414.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (13.0) (10.4)
Securities in an unrealized loss position for more than twelve months, Fair value 96.8 91.7
Total, Gross unrealized losses (37.4) (26.3)
Total, Fair value $ 564.9 $ 505.9