Quarterly report pursuant to Section 13 or 15(d)

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

v3.22.1
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
Feb. 28, 2022
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 $ 1,441.1 $ 739.6
Funds held for clients' money market securities and other restricted cash equivalents, Fair value 1,441.1 739.6
AFS securities, Amortized cost 3,952.6 2,940.9
AFS securities, Gross unrealized gains 16.7 83.3
AFS securities, Gross unrealized losses (47.6) (4.0)
AFS securities, Fair value 3,921.7 3,020.2
Other, Amortized cost 30.9 26.4
Other, Gross unrealized gains 2.7 7.7
Other, Gross unrealized losses (1.2) (0.1)
Other, Fair value 32.4 34.0
Total funds held for clients and corporate investments, Amortized cost 5,424.6 3,706.9
Total funds held for clients and corporate investments, Gross unrealized gains 19.4 91.0
Total funds held for clients and corporate investments, Gross unrealized losses (48.8) (4.1)
Total funds held for clients and corporate investments, Fair value 5,395.2 3,793.8
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 72.5 86.5
AFS securities, Gross unrealized gains 0.2 1.4
AFS securities, Gross unrealized losses (0.5)  
AFS securities, Fair value 72.2 87.9
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 673.4 635.8
AFS securities, Gross unrealized gains 6.2 28.8
AFS securities, Gross unrealized losses (5.9) (0.2)
AFS securities, Fair value 673.7 664.4
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,616.5 1,669.0
AFS securities, Gross unrealized gains 6.3 33.0
AFS securities, Gross unrealized losses (33.1) (2.3)
AFS securities, Fair value 1,589.7 1,699.7
U.S. Government Agency Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 541.0 549.6
AFS securities, Gross unrealized gains 4.0 20.1
AFS securities, Gross unrealized losses (8.1) (1.5)
AFS securities, Fair value 536.9 $ 568.2
Variable Rate Demand Notes [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,049.2  
AFS securities, Fair value $ 1,049.2