Goodwill and Other Intangibles (Details) - Schedule of other intangible assets subject to amortization - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Aug. 31, 2015	Aug. 31, 2014	May. 31, 2014	May. 31, 2015
Intangible Assets, Net (Excluding Goodwill) [Abstract]
Begining balance			$ 5.8	$ 4.7
Additions	$ 0.5	$ 0.6	0.8
Amortization expense	(0.5)	(0.5)	$ (1.9)
Total other intangibles subject to amortization, net of accumulated amortization of $17.8, $17.3 and $15.8, respectively	4.7	5.9		4.7
Total other intangibles not subject to amortization	2.1	2.1		2.1
Total other intangibles	6.8	8.0		6.8
Accumulated amortization	$ 17.8	$ 15.8		$ 17.3