Quarterly report pursuant to Section 13 or 15(d)

Funds Held for Clients and Corporate Investments (Details 2)

v3.3.1.900
Funds Held for Clients and Corporate Investments (Details 2)
$ in Millions
 3 Months Ended 9 Months Ended
Feb. 29, 2016
USD ($)
Security
Feb. 28, 2015
USD ($)
Feb. 29, 2016
USD ($)
Security
Feb. 28, 2015
USD ($)
May. 31, 2015
USD ($)
Security
Maturity Date:          
Due in one year or less, Amortized cost $ 368.5   $ 368.5    
Due in one year or less, Fair value 370.7   370.7    
Due after one year through three years, Amortized cost 678.0   678.0    
Due after one year through three years, Fair value 686.2   686.2    
Due after three years through five years, Amortized cost 888.4   888.4    
Due after three years through five years, Fair value 909.7   909.7    
Due after five years, Amortized cost 987.3   987.3    
Due after five years, Fair value 1,016.6   1,016.6    
Total, Amortized cost 2,922.2   2,922.2    
Fair value 2,983.2   2,983.2   $ 3,595.6
Funds Held for Clients and Corporate Investments (Textual)          
Net unrealized gain on available-for-sale securities $ 61.0   $ 61.0   $ 13.6
Number of available-for-sale securities in an unrealized loss position | Security 27   27   280
Gross realized gains $ 0.1 $ 0.0 $ 0.1 $ 0.2  
Gross realized losses $ 0.0 $ 0.0 $ 0.0 $ 0.0  
Minimum maturity period for VRDNs primarily categorized as due after five years (in years)     20 years    
Maximum maturity period for VRDNs, primarily categorized as due after five years (in years)     30 years