Earnings (Loss) Per Share (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended	51 Months Ended	3 Months Ended		6 Months Ended
	Nov. 30, 2014	Nov. 30, 2014	Nov. 30, 2014	Nov. 30, 2013	Nov. 30, 2013
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	0
Stock Repurchase Program, Remaining Authorized Repurchase Amount	$ 9.9	$ 9.9
Participating Restricted Stock Units [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Undistributed Earnings Allocated to Participating Securities	$ 0		$ 0	$ 0	$ 0