Annual report pursuant to Section 13 and 15(d)

Funds Held for Clients and Corporate Investments (Details 2)

v3.2.0.727
Funds Held for Clients and Corporate Investments (Details 2)
$ in Millions
 3 Months Ended 12 Months Ended
May. 31, 2015
USD ($)
Security
Feb. 28, 2015
USD ($)
Nov. 30, 2014
USD ($)
Aug. 31, 2014
USD ($)
May. 31, 2014
USD ($)
Security
Feb. 28, 2014
USD ($)
Nov. 30, 2013
USD ($)
Aug. 31, 2013
USD ($)
May. 31, 2015
USD ($)
Security
May. 31, 2014
USD ($)
Security
May. 31, 2013
USD ($)
Funds Held for Clients and Corporate Investments [Abstract]                      
Gross realized gains                 $ 0.3 $ 0.6 $ 0.9
Gross realized losses                 0.0 0.0 0.0
Net realized gains $ 0.1 $ 0.0 $ 0.1 $ 0.1 $ 0.1 $ 0.3 $ 0.0 $ 0.2 0.3 0.6 $ 0.9
Maturity Date:                      
Due in one year or less, Amortized cost 345.8               345.8    
Due in one year or less, Fair value 347.8               347.8    
Due after one year through three years, Amortized cost 726.3               726.3    
Due after one year through three years, Fair value 734.3               734.3    
Due after three years through five years, Amortized cost 800.9               800.9    
Due after three years through five years, Fair value 802.0               802.0    
Due after five years, Amortized cost 1,709.0               1,709.0    
Due after five years, Fair value 1,711.5               1,711.5    
Total, Amortized cost 3,582.0               3,582.0    
Fair value 3,595.6       3,391.4       3,595.6 3,391.4  
Funds Held for Clients and Corporate Investments (Textual)                      
Net unrealized gain on available-for-sale securities $ 13.6       $ 34.5       $ 13.6 $ 34.5  
Number of available-for-sale securities in an unrealized loss position | Security 280       98       280 98  
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    
Total, Gross unrealized losses $ (7.5)       $ (3.0)       $ (7.5) $ (3.0)