Common Stock and Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2014		May 31, 2013		May 31, 2012
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 177		$ 174		$ 130
Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	125	[1]	123	[1]	96	[1]
ESPPs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	22		19		16
Restricted Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 30		$ 32		$ 18

[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, 2014, 2013, and 2012 was $15 million, $22 million, and $17 million, respectively.