Consolidated Condensed Balance Sheets (Unaudited) (Parenthetical)	Nov. 30, 2012	May 31, 2012
Statement of Financial Position [Abstract]
Preferred stock, shares authorized (in shares)	100,000	100,000
Preferred stock, shares outstanding ( in shares)	0	0
Common stock, shares authorized (in shares)	425,000,000	425,000,000
Common stock, shares issued (in shares)	174,419,454	173,745,913
Common stock, shares outstanding (in shares)	123,228,777	126,519,758
Treasury stock, shares (in shares)	51,190,677	47,226,155