Annual report pursuant to Section 13 and 15(d)

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

v3.23.2
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
May 31, 2023
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 $ (15.2) $ (116.2)
Securities in an unrealized loss position for less than twelve months, Fair value 992.5 2,059.6
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (164.2) (22.8)
Securities in an unrealized loss position for more than twelve months, Fair value 1,752.9 200.7
Total, Gross unrealized losses (179.4) (139.0)
Total, Fair value 2,745.4 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 (0.1) (0.9)
Securities in an unrealized loss position for less than twelve months, Fair value 54.2 48.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (1.3) (0.3)
Securities in an unrealized loss position for more than twelve months, Fair value 23.3 5.7
Total, Gross unrealized losses (1.4) (1.2)
Total, Fair value 77.5 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 (5.9) (17.5)
Securities in an unrealized loss position for less than twelve months, Fair value 652.0 425.4
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (25.2) (1.5)
Securities in an unrealized loss position for more than twelve months, Fair value 382.7 16.7
Total, Gross unrealized losses (31.1) (19.0)
Total, Fair value 1,034.7 442.1
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 (5.9) (81.9)
Securities in an unrealized loss position for less than twelve months, Fair value 86.7 1,171.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (99.4) (10.6)
Securities in an unrealized loss position for more than twelve months, Fair value 889.0 86.6
Total, Gross unrealized losses (105.3) (92.5)
Total, Fair value 975.7 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 (3.3) (15.9)
Securities in an unrealized loss position for less than twelve months, Fair value 199.6 414.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (38.3) (10.4)
Securities in an unrealized loss position for more than twelve months, Fair value 457.9 91.7
Total, Gross unrealized losses (41.6) (26.3)
Total, Fair value $ 657.5 $ 505.9