Quarterly report [Sections 13 or 15(d)]

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

v3.26.3
Funds Held for Clients and Corporate Investments (Securities in Unrealized Loss Position) (Details) - USD ($)
$ in Millions
Aug. 31, 2026
May 31, 2026
Schedule of Available-for-sale Securities [Line Items]    
Securities in an unrealized loss position for less than twelve months, Gross unrealized losses $ (67.5) $ (31.5)
Securities in an unrealized loss position for less than twelve months, Fair value 2,765.6 1,850.2
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (26.7) (28.3)
Securities in an unrealized loss position for more than twelve months, Fair value 1,042.6 1,178.5
Total, Gross unrealized losses (94.2) (59.8)
Total, Fair value 3,808.2 3,028.7
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 (0.3) (0.1)
Securities in an unrealized loss position for less than twelve months, Fair value 29.8 21.7
Total, Gross unrealized losses (0.3) (0.1)
Total, Fair value 29.8 21.7
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 (41.4) (16.3)
Securities in an unrealized loss position for less than twelve months, Fair value 1,748.9 1,148.8
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (2.2) (2.5)
Securities in an unrealized loss position for more than twelve months, Fair value 102.3 128.0
Total, Gross unrealized losses (43.6) (18.8)
Total, Fair value 1,851.2 1,276.8
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 (2.2) (1.7)
Securities in an unrealized loss position for less than twelve months, Fair value 135.2 69.0
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (17.8) (19.4)
Securities in an unrealized loss position for more than twelve months, Fair value 637.6 713.2
Total, Gross unrealized losses (20.0) (21.1)
Total, Fair value 772.8 782.2
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 (23.6) (13.4)
Securities in an unrealized loss position for less than twelve months, Fair value 851.7 610.7
Securities in an unrealized loss position for more than twelve months, Gross unrealized losses (6.7) (6.4)
Securities in an unrealized loss position for more than twelve months, Fair value 302.7 337.3
Total, Gross unrealized losses (30.3) (19.8)
Total, Fair value $ 1,154.4 $ 948.0