Quarterly report pursuant to Section 13 or 15(d)

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

v3.24.3
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
Aug. 31, 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 $ (4.5) $ (23.0)
Securities in an unrealized loss position for less than twelve months, Fair value 116.1 1,068.9
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (93.5) (141.2)
Securities in an unrealized loss position for more than twelve months, Fair value 1,889.9 2,102.7
Total, Gross unrealized losses (98.0) (164.2)
Total, Fair value 2,006.0 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 2.4 77.4
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (0.3) (0.7)
Securities in an unrealized loss position for more than twelve months, Fair value 25.0 43.0
Total, Gross unrealized losses (0.3) (1.1)
Total, Fair value 27.4 120.4
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 (0.1) (8.4)
Securities in an unrealized loss position for less than twelve months, Fair value 14.4 620.8
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (12.3) (24.4)
Securities in an unrealized loss position for more than twelve months, Fair value 424.7 647.8
Total, Gross unrealized losses (12.4) (32.8)
Total, Fair value 439.1 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 (4.3) (8.0)
Securities in an unrealized loss position for less than twelve months, Fair value 59.4 102.5
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (57.1) (78.9)
Securities in an unrealized loss position for more than twelve months, Fair value 910.1 864.7
Total, Gross unrealized losses (61.4) (86.9)
Total, Fair value 969.5 967.2
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 (0.1) (6.2)
Securities in an unrealized loss position for less than twelve months, Fair value 39.9 268.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (23.8) (37.2)
Securities in an unrealized loss position for more than twelve months, Fair value 530.1 547.2
Total, Gross unrealized losses (23.9) (43.4)
Total, Fair value $ 570.0 $ 815.4