Stock-Based Compensation Plans (Stock Option Activity) (Details) - Stock Options [Member] $ / shares in Units, shares in Millions, $ in Millions	12 Months Ended
	May 31, 2016 USD ($) $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Outstanding, Beginning balance, Shares subject to options | shares	4.7
Granted, Shares subject to options | shares	0.8
Exercised, Shares subject to options | shares	(0.9)
Forfeited, Shares subject to options | shares	(0.1)
Expired, Shares subject to options | shares
Outstanding, Ending balance, Shares subject to options | shares	4.5
Exercisable, Shares subject to options | shares	2.6
Outstanding, Beginning balance, Weighted-average exercise price per share | $ / shares	$ 35.21
Granted, Weighted-average exercise price per share | $ / shares	47.42
Exercised, Weighted-average exercise price per share | $ / shares	34.77
Forfeited, Weighted-average exercise price per share | $ / shares	38.46
Expired, Weighted-average exercise price per share | $ / shares	35.89
Outstanding, Ending balance, Weighted-average exercise price per share | $ / shares	37.42
Exercisable, Weighted-average exercise price per share | $ / shares	$ 33.84
Outstanding, Weighted-average remaining contractual term (years)	6 years 3 months 18 days
Exercisable, Weighted-average remaining contractual term (years)	4 years 10 months 24 days
Outstanding, Aggregate intrinsic value | $	$ 75.9	[1]
Exercisable, Aggregate intrinsic value | $	$ 53.1	[1]

[1] Market price of the underlying stock as of May 31, 2016 less the exercise price.