Income Taxes (Details) $ in Millions	3 Months Ended
	Aug. 31, 2015 USD ($)
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, period increase	$ 0.5
Unrecognized tax benefits, increase in accrued interest (less than)	0.1
Decrease in unrecognized tax benefit reasonably possible in the next twelve months	$ 3.4