Earnings (Loss) Per Share (Details) - Schedule of Earnings Per Share, Basic and Diluted (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	May 31, 2013	May 31, 2012	May 31, 2011
Schedule of Earnings Per Share, Basic and Diluted [Abstract]
Earnings (loss) from continuing operations attributable to Class A and Common Shares (in Dollars)	$ 35.7	$ 107.6	$ 45.0
Earnings (loss) from discontinued operations attributable to Class A and Common Shares, net of tax (in Dollars)	(4.7)	(5.7)	(5.9)
Net income (loss) attributable to Class A and Common Shares (in Dollars)	$ 31.0	$ 101.9	$ 39.1
Weighted average Shares of Class A Stock and Common Stock outstanding for basic earnings (loss) per share (in millions) (in Shares)	31.8	31.2	33.1
Dilutive effect of Class A Stock and Common Stock potentially issuable pursuant to stock-based compensation plans (in millions) (in Shares)	0.6	0.5	0.5
Adjusted weighted average Shares of Class A Stock and Common Stock outstanding for diluted earnings (loss) per share (in millions) (in Shares)	32.4	31.7	33.6
Basic earnings (loss) per share:
Earnings (loss) from continuing operations	$ 1.12	$ 3.45	$ 1.36
Earnings (loss) from discontinued operations, net of tax	$ (0.15)	$ (0.18)	$ (0.18)
Net income (loss)	$ 0.97	$ 3.27	$ 1.18
Diluted earnings (loss) per share:
Earnings (loss) from continuing operations	$ 1.10	$ 3.39	$ 1.34
Earnings (loss) from discontinued operations, net of tax	$ (0.15)	$ (0.18)	$ (0.18)
Net income (loss)	$ 0.95	$ 3.21	$ 1.16