Annual report pursuant to Section 13 and 15(d)

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

v3.19.2
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
May 31, 2019
May 31, 2018
Schedule of Available-for-sale Securities [Line Items]    
Funds held for clients' money market securities and other cash equivalents, Amortized cost $ 204.5 $ 1,942.3
Funds held for clients' money market securities and other cash equivalents, Gross unrealized gains
Funds held for clients' money market securities and other cash equivalents, Gross unrealized losses
Funds held for clients' money market securities and other cash equivalents, Fair value 204.5 1,942.3
Available-for-sale securities, Amortized cost 3,601.1 3,143.1
Available-for-sale securities, Gross unrealized gains 22.4 2.4
Available-for-sale securities, Gross unrealized losses (2.7) (40.7)
Available-for-sale securities, Fair value 3,620.8 3,104.8
Other, Amortized cost 26.3 16.1
Other, Gross unrealized gains 1.7 2.1
Other, Gross unrealized losses (0.3)
Other, Fair value 27.7 18.2
Total funds held for clients and corporate investments, Amortized cost 3,831.9 5,101.5
Total funds held for clients and corporate investments, Gross unrealized gains 24.1 4.5
Total funds held for clients and corporate investments, Gross unrealized losses (3.0) (40.7)
Total funds held for clients and corporate investments, Fair value 3,853.0 5,065.3
Asset-backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 5.3  
Available-for-sale securities, Gross unrealized gains  
Available-for-sale securities, Gross unrealized losses  
Available-for-sale securities, Fair value 5.3  
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 442.1 328.6
Available-for-sale securities, Gross unrealized gains 5.3 0.1
Available-for-sale securities, Gross unrealized losses (0.9) (7.3)
Available-for-sale securities, Fair value 446.5 321.4
General Obligation Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 840.6 1,231.6
Available-for-sale securities, Gross unrealized gains 7.5 1.3
Available-for-sale securities, Gross unrealized losses (0.3) (11.2)
Available-for-sale securities, Fair value 847.8 1,221.7
Pre-Refunded Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost [1] 25.6 50.9
Available-for-sale securities, Gross unrealized gains [1] 0.2 0.1
Available-for-sale securities, Gross unrealized losses [1] (0.1)
Available-for-sale securities, Fair value [1] 25.8 50.9
Revenue Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 545.4 813.5
Available-for-sale securities, Gross unrealized gains 4.7 0.9
Available-for-sale securities, Gross unrealized losses (0.2) (8.0)
Available-for-sale securities, Fair value 549.9 806.4
U.S. Government Agency And Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 612.5 410.2
Available-for-sale securities, Gross unrealized gains 4.7  
Available-for-sale securities, Gross unrealized losses (1.3) (14.1)
Available-for-sale securities, Fair value 615.9 396.1
Variable Rate Demand Notes [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 1,129.6 308.3
Available-for-sale securities, Gross unrealized gains
Available-for-sale securities, Gross unrealized losses
Available-for-sale securities, Fair value $ 1,129.6 $ 308.3
[1] Pre-refunded municipal bonds are secured by an escrow fund of U.S. government obligations.