Common Stock and Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2013		May 31, 2012		May 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 174		$ 130		$ 105
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	123	[1]	96	[1]	77	[1]
ESPPs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	19		16		14
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 32		$ 18		$ 14

[1] Expense for stock options includes the expense associated with stock appreciation rights. Accelerated stock option expense is recorded for employees eligible for accelerated stock option vesting upon retirement. Accelerated stock option expense for years ended May 31, 2013, 2012, and 2011 was $22 million, $17 million, and $12 million, respectively.