Quarterly report pursuant to Section 13 or 15(d)

Short-term Financing (Amount Borrowed) (Details)

v3.5.0.2
Short-term Financing (Amount Borrowed) (Details) - Revolving Credit Facility [Member] - USD ($)
$ in Millions
3 Months Ended
Aug. 31, 2016
Aug. 31, 2015
Line of Credit Facility [Line Items]    
Number of days borrowed 4 days 1 day
Maximum amount borrowed $ 350.0 $ 200.0
Weighted-average amount borrowed $ 237.5 $ 200.0
Weighted-average interest rate 3.50% 3.25%
PNC Bank, National Association [Member]    
Line of Credit Facility [Line Items]    
Weighted-average number of days borrowed 84 days  
Maximum amount borrowed $ 51.3  
Weighted-average amount borrowed $ 51.3  
Weighted-average interest rate 1.01%