Total Stock-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Feb. 29, 2012		Feb. 28, 2011		Feb. 29, 2012		Feb. 28, 2011
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock Options	$ 26	[1]	$ 21	[1]	$ 70	[1]	$ 56	[1]
ESPPs	4		3		12		11
Restricted Stock	4		4		13		11
Total stock-based compensation expense	$ 34		$ 28		$ 95		$ 78

[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 the three and nine month periods ended February 29, 2012 was $4 million and $12 million, respectively. The accelerated stock option expense for the three and nine month periods ended February 28, 2011 was $3 million and $9 million, respectively.