Annual report pursuant to Section 13 and 15(d)

Stock Based Compensation Plans (Details 3)

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Stock Based Compensation Plans (Details 3) (Restricted Stock Awards [Member], USD $)
In Millions, except Per Share data
12 Months Ended
May 31, 2011
May 31, 2010
May 31, 2009
Restricted Stock Awards [Member]
     
Restricted stock unit activity      
Nonvested/ unearned shares outstanding, Beginning balance 0.4 0.2 0.2
Nonvested/ unearned shares, weighted-average grant date fair value per share, Beginning balance $ 31.95 $ 36.74 $ 41.48
Granted 0.1 0.2 0.1
Granted, Weighted-average grant-date fair value per share $ 26.40 $ 24.60 $ 31.76
Vested (0.1)   (0.1)
Vested, Weighted-average grant-date fair value per share $ 35.60 $ 35.79 $ 39.82
Forfeited (0.1)    
Forfeited, Weighted-average grant-date fair value per share $ 30.02 $ 32.66 $ 36.81
Nonvested/ unearned shares outstanding, Weighted-average grant-date fair value per share, Ending balance $ 29.88 $ 31.95 $ 36.74
Nonvested/ unearned shares outstanding, Ending balance 0.3 0.4 0.2