Quarterly report pursuant to Section 13 or 15(d)

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

v3.21.2
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
Aug. 31, 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 $ 789.1 $ 739.6
Funds held for clients' money market securities and other restricted cash equivalents, Fair value 789.1 739.6
AFS securities, Amortized cost 2,923.7 2,940.9
AFS securities, Gross unrealized gains 80.5 83.3
AFS securities, Gross unrealized losses (1.8) (4.0)
AFS securities, Fair value 3,002.4 3,020.2
Other, Amortized cost 29.7 26.4
Other, Gross unrealized gains 7.2 7.7
Other, Gross unrealized losses   (0.1)
Other, Fair value 36.9 34.0
Total funds held for clients and corporate investments, Amortized cost 3,742.5 3,706.9
Total funds held for clients and corporate investments, Gross unrealized gains 87.7 91.0
Total funds held for clients and corporate investments, Gross unrealized losses (1.8) (4.1)
Total funds held for clients and corporate investments, Fair value 3,828.4 3,793.8
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 79.9 86.5
AFS securities, Gross unrealized gains 1.2 1.4
AFS securities, Fair value 81.1 87.9
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 648.8 635.8
AFS securities, Gross unrealized gains 25.5 28.8
AFS securities, Gross unrealized losses (0.2) (0.2)
AFS securities, Fair value 674.1 664.4
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 1,669.2 1,669.0
AFS securities, Gross unrealized gains 34.5 33.0
AFS securities, Gross unrealized losses (0.7) (2.3)
AFS securities, Fair value 1,703.0 1,699.7
U.S. Government Agency And Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
AFS securities, Amortized cost 525.8 549.6
AFS securities, Gross unrealized gains 19.3 20.1
AFS securities, Gross unrealized losses (0.9) (1.5)
AFS securities, Fair value $ 544.2 $ 568.2