Commitments and Contingencies (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Oct. 03, 2003	May. 31, 2015	May. 31, 2015	May. 31, 2014
Sale-leaseback transaction
Net proceeds from sale of facility			$ 40.3
Garden City lease
Sale-leaseback transaction
Net proceeds from sale of facility	$ 14.0	$ 40.3
Cost of the facility	9.5
Accumulated depreciation of the facility	4.6
Deferred gain realized on the sale	$ 9.1
Deferred gain amortization period	20 years	2 years
Unamortized balance of the deferred gain		$ 3.8	$ 3.8	$ 4.3