Annual report pursuant to Section 13 and 15(d)

Income Taxes (Details Textual)

v3.2.0.727
Income Taxes (Details Textual) - USD ($)
$ in Millions
12 Months Ended
May. 31, 2013
May. 31, 2015
May. 31, 2014
Income Taxes (Details Textual) [Abstract]      
Total reserve for uncertain tax positions   $ 29.1 $ 29.8
Total reserve for uncertain tax positions included in long-term liabilities   29.1 28.6
Reserve for uncertain tax positions, increase in May 2013 $ 21.2    
Impact of uncertain tax positions, if recognized, on company's effective income tax rate   $ 29.1 $ 24.6