Quarterly report pursuant to Section 13 or 15(d)

Funds Held for Clients and Corporate Investments (Details 2)

v2.4.0.8
Funds Held for Clients and Corporate Investments (Details 2) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Nov. 30, 2013
Security
Nov. 30, 2012
Nov. 30, 2013
Security
Nov. 30, 2012
May 31, 2013
Security
Maturity Date:          
Due in one year or less, Amortized cost $ 337.4   $ 337.4    
Due in one year or less, Fair value 340.2   340.2    
Due after one year through three years, Amortized cost 742.1   742.1    
Due after one year through three years, Fair value 760.2   760.2    
Due after three years through five years, Amortized cost 736.7   736.7    
Due after three years through five years, Fair value 745.9   745.9    
Due after five years, Amortized cost 992.8   992.8    
Due after five years, Fair value 984.2   984.2    
Total, Amortized cost 2,809.0   2,809.0    
Fair value 2,830.5   2,830.5   3,691.4
Funds Held for Clients and Corporate Investments (Textual)          
Net unrealized gain on available-for-sale securities 21.5   21.5   34.7
Number of available-for-sale securities in an unrealized loss position 192   192   147
Gross realized gains 0 0.1 0.2 0.3  
Gross realized losses $ 0 $ 0 $ 0 $ 0  
Minimum maturity period for VRDNs primarily categorized as due after five years (in years) 20 years   20 years    
Maximum maturity period for VRDNs, primarily categorized as due after five years (in years) 30 years   30 years