Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.4
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
Nov. 30, 2021
May 31, 2021
Schedule of Available-for-sale Securities [Line Items]    
Funds held for clients' money market securities and other restricted cash equivalents, Amortized cost $ 905.6 $ 739.6
Funds held for clients' money market securities and other restricted cash equivalents, Fair value 905.6 739.6
AFS securities, Amortized cost 3,281.2 2,940.9
AFS securities, Gross unrealized gains 50.5 83.3
AFS securities, Gross unrealized losses (14.6) (4.0)
AFS securities, Fair value 3,317.1 3,020.2
Other, Amortized cost 30.2 26.4
Other, Gross unrealized gains 4.9 7.7
Other, Gross unrealized losses (0.2) (0.1)
Other, Fair value 34.9 34.0
Total funds held for clients and corporate investments, Amortized cost 4,217.0 3,706.9
Total funds held for clients and corporate investments, Gross unrealized gains 55.4 91.0
Total funds held for clients and corporate investments, Gross unrealized losses (14.8) (4.1)
Total funds held for clients and corporate investments, Fair value 4,257.6 3,793.8
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 76.5 86.5
AFS securities, Gross unrealized gains 0.7 1.4
AFS securities, Gross unrealized losses (0.2)  
AFS securities, Fair value 77.0 87.9
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 664.9 635.8
AFS securities, Gross unrealized gains 17.2 28.8
AFS securities, Gross unrealized losses (1.6) (0.2)
AFS securities, Fair value 680.5 664.4
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,678.6 1,669.0
AFS securities, Gross unrealized gains 20.3 33.0
AFS securities, Gross unrealized losses (9.5) (2.3)
AFS securities, Fair value 1,689.4 1,699.7
U.S. Government Agency Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 522.7 549.6
AFS securities, Gross unrealized gains 12.3 20.1
AFS securities, Gross unrealized losses (3.3) (1.5)
AFS securities, Fair value 531.7 $ 568.2
Variable Rate Demand Notes [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 338.5  
AFS securities, Fair value $ 338.5