v3.26.1
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
May 31, 2026
May 31, 2025
Schedule of Available-for-sale Securities [Line Items]    
Funds held for clients' money market securities and other restricted cash equivalents, Amortized cost $ 343.8 $ 1,057.8
Funds held for clients' money market securities and other restricted cash equivalents, Fair value 343.8 1,057.8
AFS securities, Amortized cost 4,540.9 3,809.1
AFS securities, Gross unrealized gains 7.3 14.4
AFS securities, Gross unrealized losses (59.8) (68.0)
AFS securities, Fair value 4,488.4 3,755.5
Other, Amortized cost 32.3 33.1
Other, Gross unrealized gains 4.6 2.3
Other, Gross unrealized losses (0.6) (0.9)
Other, Fair value 36.3 34.5
Total funds held for clients and corporate investments, Amortized cost 4,917.0 4,900.0
Total funds held for clients and corporate investments, Gross unrealized gains 11.9 16.7
Total funds held for clients and corporate investments, Gross unrealized losses (60.4) (68.9)
Total funds held for clients and corporate investments, Fair value 4,868.5 4,847.8
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 106.5 158.3
AFS securities, Gross unrealized gains 0.4 0.9
AFS securities, Gross unrealized losses (0.1) 0.0
AFS securities, Fair value 106.8 159.2
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 2,349.9 1,640.3
AFS securities, Gross unrealized gains 5.5 10.7
AFS securities, Gross unrealized losses (18.8) (7.0)
AFS securities, Fair value 2,336.6 1,644.0
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 851.9 1,017.3
AFS securities, Gross unrealized gains 0.4 0.5
AFS securities, Gross unrealized losses (21.1) (44.3)
AFS securities, Fair value 831.2 973.5
U.S. Government Agency And Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,232.6 993.2
AFS securities, Gross unrealized gains 1.0 2.3
AFS securities, Gross unrealized losses (19.8) (16.7)
AFS securities, Fair value $ 1,213.8 $ 978.8