Treasury Stock (Details) (USD $) In Millions, except Share data, unless otherwise specified	1 Months Ended	12 Months Ended
	Sep. 30, 2010	May 31, 2013	May 31, 2012	May 31, 2011
Treasury Stock [Text Block]
Accelerated Share Repurchases Outstanding Common Stock	$ 200.0
Common Shares Purchased (in Shares)				5,199,699
Common Shares Purchase Price Per Share (in Dollars per share)				$ 30.00
Purchase Of Common Stock Value Excluding Related Fees and Expenses				156.0
Treasury Stock, Shares, Acquired (in Shares)		400,000
Treasury Stock, Value, Acquired, Cost Method		$ (11.8)	$ (13.1)	$ (166.9)
Treasury Stock Acquired, Average Cost Per Share (in Dollars per share)		$ 27.34