Annual report pursuant to Section 13 and 15(d)

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

v3.20.2
Funds Held for Clients and Corporate Investments (Funds Held for Clients and Corporate Investments) (Details) - USD ($)
$ in Millions
May 31, 2020
May 31, 2019
Schedule of Available-for-sale Securities [Line Items]    
Funds held for clients' money market securities and other cash equivalents, Amortized cost $ 683.5 $ 204.5
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 683.5 204.5
Available-for-sale securities, Amortized cost 2,657.2 3,601.1
Available-for-sale securities, Gross unrealized gains 101.7 22.4
Available-for-sale securities, Gross unrealized losses (1.7) (2.7)
Available-for-sale securities, Fair value 2,757.2 3,620.8
Other, Amortized cost 25.4 26.3
Other, Gross unrealized gains 2.2 1.7
Other, Gross unrealized losses (0.4) (0.3)
Other, Fair value 27.2 27.7
Total funds held for clients and corporate investments, Amortized cost 3,366.1 3,831.9
Total funds held for clients and corporate investments, Gross unrealized gains 103.9 24.1
Total funds held for clients and corporate investments, Gross unrealized losses (2.1) (3.0)
Total funds held for clients and corporate investments, Fair value 3,467.9 3,853.0
Asset-Backed Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 68.0 5.3
Available-for-sale securities, Gross unrealized gains 1.7  
Available-for-sale securities, Gross unrealized losses  
Available-for-sale securities, Fair value 69.7 5.3
Corporate Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 649.6 442.1
Available-for-sale securities, Gross unrealized gains 34.1 5.3
Available-for-sale securities, Gross unrealized losses (0.1) (0.9)
Available-for-sale securities, Fair value 683.6 446.5
Municipal Bonds [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 1,373.8 1,411.6
Available-for-sale securities, Gross unrealized gains 37.4 12.4
Available-for-sale securities, Gross unrealized losses (1.6) (0.5)
Available-for-sale securities, Fair value 1,409.6 1,423.5
U.S. Government Agency And Treasury Securities [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost 565.8 612.5
Available-for-sale securities, Gross unrealized gains 28.5 4.7
Available-for-sale securities, Gross unrealized losses   (1.3)
Available-for-sale securities, Fair value $ 594.3 615.9
Variable Rate Demand Notes [Member]    
Schedule of Available-for-sale Securities [Line Items]    
Available-for-sale securities, Amortized cost   1,129.6
Available-for-sale securities, Gross unrealized gains  
Available-for-sale securities, Gross unrealized losses  
Available-for-sale securities, Fair value   $ 1,129.6