Stock-Based Compensation (Details) - Schedule of stock-based compensation - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2015	Aug. 31, 2014
Stock-Based Compensation (Details) - Schedule of stock-based compensation [Line Items]
Stock option expense	$ 0.7	$ 0.8
Restricted stock unit expense	0.6	0.7
Stock-based compensation expense	$ 1.4	$ 1.6
Share-based payment awards, options, by number of shares issued from Treasury Stock	1.0	0.5
Discontinued Operations
Stock-Based Compensation (Details) - Schedule of stock-based compensation [Line Items]
Stock-based compensation expense	$ 0.0	$ 0.2
Management Stock Purchase Plan
Stock-Based Compensation (Details) - Schedule of stock-based compensation [Line Items]
Stock-based compensation expense	0.0	0.0
Employee Stock Purchase Plan
Stock-Based Compensation (Details) - Schedule of stock-based compensation [Line Items]
Stock-based compensation expense	$ 0.1	$ 0.1