Total Stock Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2012		Aug. 31, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 37		$ 25
Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	26	[1]	18	[1]
ESPPs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	4		3
Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7		$ 4

[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 was $4 million for each of the three month periods ended August 31, 2012 and 2011.