Annual report pursuant to Section 13 and 15(d)

Commitments and Contingencies (Amount Borrowed) (Details)

v3.5.0.2
Commitments and Contingencies (Amount Borrowed) (Details) - Revolving Credit Facility [Member] - USD ($)
$ in Millions
12 Months Ended
May 31, 2016
May 31, 2015
Line of Credit Facility [Line Items]    
Number of days borrowed 5 days 2 days
Maximum amount borrowed $ 450.0 $ 150.0
Average amount borrowed $ 305.0 $ 125.0
Weighted-average interest rate 3.39% 3.25%