Income Taxes (Details) $ in Millions	3 Months Ended	6 Months Ended
	Nov. 30, 2015 USD ($)	Nov. 30, 2015 USD ($)
Income Tax Disclosure [Abstract]
Unrecognized tax benefits, period increase	$ 0.6	$ 1.1
Unrecognized tax benefits, increase in accrued interest	0.1	0.2
Decrease in unrecognized tax benefit reasonably possible in the next twelve months	$ 1.0	$ 1.0