Quarterly report pursuant to Section 13 or 15(d)

Income Taxes Income Taxes (Details)

Income Taxes Income Taxes (Details)
3 Months Ended
Aug. 31, 2015
Aug. 31, 2014
Income Tax Disclosure [Abstract]    
Effective income tax rate 29.70% 36.30%
Effective income tax rate, excluding tax benefit related to prior years 36.00%  
Federal statutory income tax rate 35.00%