Consolidated Condensed Balance Sheets (Unaudited) (Parenthetical) (USD $)	Aug. 31, 2014	May 31, 2014
Statement of Financial Position [Abstract]
Preferred stock, no par value (dollars per share)	$ 0	$ 0
Preferred stock, shares authorized (shares)	100,000	100,000
Preferred stock, shares outstanding (shares)	0	0
Common stock, no par value (dollars per share)	$ 0	$ 0
Common stock, shares authorized (shares)	425,000,000	425,000,000
Common stock, shares issued (shares)	175,315,907	176,378,412
Common stock, shares outstanding (shares)	116,991,574	117,037,784
Treasury stock, shares (shares)	60,324,333	59,340,628