Annual report [Section 13 and 15(d), not S-K Item 405]

Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details)

v3.25.2
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
May 31, 2025
May 31, 2024
Schedule of Available-for-sale Securities [Line Items]    
Funds held for clients' money market securities and other restricted cash equivalents, Amortized cost $ 1,057.8 $ 380.3
Funds held for clients' money market securities and other restricted cash equivalents, Fair value 1,057.8 380.3
AFS securities, Amortized cost 3,809.1 3,492.1
AFS securities, Gross unrealized gains 14.4 1.7
AFS securities, Gross unrealized losses (68.0) (164.2)
AFS securities, Fair value 3,755.5 3,329.6
Other, Amortized cost 33.1 32.3
Other, Gross unrealized gains 2.3 3.2
Other, Gross unrealized losses (0.9) (1.6)
Other, Fair value 34.5 33.9
Total funds held for clients and corporate investments, Amortized cost 4,900.0 3,904.7
Total funds held for clients and corporate investments, Gross unrealized gains 16.7 4.9
Total funds held for clients and corporate investments, Gross unrealized losses (68.9) (165.8)
Total funds held for clients and corporate investments, Fair value 4,847.8 3,743.8
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 158.3 135.7
AFS securities, Gross unrealized gains 0.9 0.1
AFS securities, Gross unrealized losses 0.0 (1.1)
AFS securities, Fair value 159.2 134.7
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,640.3 1,400.3
AFS securities, Gross unrealized gains 10.7 1.3
AFS securities, Gross unrealized losses (7.0) (32.8)
AFS securities, Fair value 1,644.0 1,368.8
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,017.3 1,060.1
AFS securities, Gross unrealized gains 0.5 0.2
AFS securities, Gross unrealized losses (44.3) (86.9)
AFS securities, Fair value 973.5 973.4
U.S. Government Agency And Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 993.2 896.0
AFS securities, Gross unrealized gains 2.3 0.1
AFS securities, Gross unrealized losses (16.7) (43.4)
AFS securities, Fair value $ 978.8 $ 852.7