Quarterly report pursuant to Section 13 or 15(d)

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

v3.24.4
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
Nov. 30, 2024
May 31, 2024
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses $ (5.3) $ (23.0)
Securities in an unrealized loss position for less than twelve months, Fair value 601.4 1,068.9
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (89.9) (141.2)
Securities in an unrealized loss position for more than twelve months, Fair value 1,783.1 2,102.7
Total, Gross unrealized losses (95.2) (164.2)
Total, Fair value 2,384.5 3,171.6
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)
Securities in an unrealized loss position for less than twelve months, Fair value 17.4 77.4
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.2) (0.7)
Securities in an unrealized loss position for more than twelve months, Fair value 8.6 43.0
Total, Gross unrealized losses (0.2) (1.1)
Total, Fair value 26.0 120.4
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 (1.3) (8.4)
Securities in an unrealized loss position for less than twelve months, Fair value 359.8 620.8
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (10.6) (24.4)
Securities in an unrealized loss position for more than twelve months, Fair value 335.8 647.8
Total, Gross unrealized losses (11.9) (32.8)
Total, Fair value 695.6 1,268.6
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 (3.2) (8.0)
Securities in an unrealized loss position for less than twelve months, Fair value 47.1 102.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (55.9) (78.9)
Securities in an unrealized loss position for more than twelve months, Fair value 912.8 864.7
Total, Gross unrealized losses (59.1) (86.9)
Total, Fair value 959.9 967.2
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) (6.2)
Securities in an unrealized loss position for less than twelve months, Fair value 177.1 268.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (23.2) (37.2)
Securities in an unrealized loss position for more than twelve months, Fair value 525.9 547.2
Total, Gross unrealized losses (24.0) (43.4)
Total, Fair value $ 703.0 $ 815.4