Common Stock and Stock-Based Compensation - Stock Option Transactions Under Plan (Detail) (Stock Incentive Plan 1990 [Member], USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	May 31, 2013		May 31, 2012		May 31, 2011
Stock Incentive Plan 1990 [Member]
Options Outstanding - Shares
Beginning Balance (in shares)	64.3	[1]	69.6	[1]	72.2	[1]
Exercised (in shares)	(9.9)	[1]	(18.0)	[1]	(14.0)	[1]
Forfeited (in shares)	(1.3)	[1]	(1.0)	[1]	(1.3)	[1]
Granted (in shares)	14.6	[1]	13.7	[1]	12.7	[1]
Ending Balance (in shares)	67.7	[1]	64.3	[1]	69.6	[1]
Options exercisable (in shares)	35.9	[1]	33.9	[1]	40.1	[1]
Options Outstanding - Weighted-Average Option Price
Beginning Balance (in dollars per share)	$ 30.59		$ 25.65		$ 23.30
Exercised (in dollars per share)	$ 24.70		$ 22.81		$ 21.35
Forfeited (in dollars per share)	$ 40.14		$ 35.61		$ 29.03
Granted (in dollars per share)	$ 46.55		$ 45.87		$ 34.60
Ending Balance (in dollars per share)	$ 34.72		$ 30.59		$ 25.65
Options exercisable (in dollars per share)	$ 27.70		$ 24.38		$ 22.03

[1] Includes stock appreciation rights transactions.