Goodwill and Other Intangibles (Details) - Schedule of other intangible assets subject to amortization (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended
	Aug. 31, 2014	Aug. 31, 2013	May 31, 2014	May 31, 2013
Finite-Lived Intangible Assets [Line Items]
Total other intangibles subject to amortization	$ 10.0	$ 12.0	$ 10.0
Trademarks and other	2.2	2.0	2.2
Total other intangibles not subject to amortization	2.2	2.0	2.2
Total other intangibles	12.2	14.0	12.2
Customer Lists
Finite-Lived Intangible Assets [Line Items]
Begining balance			2.4	3.4
Additions due to acquisition	0.6	0	0
Amortization expense	(0.2)	(0.2)	(1.0)
Foreign currency translation	0	0	0
Total other intangibles subject to amortization	2.8	3.2	2.4
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Begining balance			7.6	9.2
Additions due to acquisition	0	0	0
Amortization expense	(0.4)	(0.4)	(1.4)
Foreign currency translation	0	0	0
Other	0	0	(0.2)
Total other intangibles subject to amortization	$ 7.2	$ 8.8	$ 7.6