Annual report pursuant to Section 13 and 15(d)

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

v3.24.2
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
May 31, 2024
May 31, 2023
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses $ (23.0) $ (15.2)
Securities in an unrealized loss position for less than twelve months, Fair value 1,068.9 992.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (141.2) (164.2)
Securities in an unrealized loss position for more than twelve months, Fair value 2,102.7 1,752.9
Total, Gross unrealized losses (164.2) (179.4)
Total, Fair value 3,171.6 2,745.4
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 (0.4) (0.1)
Securities in an unrealized loss position for less than twelve months, Fair value 77.4 54.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.7) (1.3)
Securities in an unrealized loss position for more than twelve months, Fair value 43.0 23.3
Total, Gross unrealized losses (1.1) (1.4)
Total, Fair value 120.4 77.5
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 (8.4) (5.9)
Securities in an unrealized loss position for less than twelve months, Fair value 620.8 652.0
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (24.4) (25.2)
Securities in an unrealized loss position for more than twelve months, Fair value 647.8 382.7
Total, Gross unrealized losses (32.8) (31.1)
Total, Fair value 1,268.6 1,034.7
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 (8.0) (5.9)
Securities in an unrealized loss position for less than twelve months, Fair value 102.5 86.7
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (78.9) (99.4)
Securities in an unrealized loss position for more than twelve months, Fair value 864.7 889.0
Total, Gross unrealized losses (86.9) (105.3)
Total, Fair value 967.2 975.7
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 (6.2) (3.3)
Securities in an unrealized loss position for less than twelve months, Fair value 268.2 199.6
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (37.2) (38.3)
Securities in an unrealized loss position for more than twelve months, Fair value 547.2 457.9
Total, Gross unrealized losses (43.4) (41.6)
Total, Fair value $ 815.4 $ 657.5