Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Aug. 31, 2014		Aug. 31, 2013
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 43		$ 42
Class B Common Stock | Stock Incentive Plan 1990
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	43		42
Class B Common Stock | Stock Incentive Plan 1990 | Stock Options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	30	[1]	29	[1]
Class B Common Stock | Stock Incentive Plan 1990 | ESPPs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	6		5
Class B Common Stock | Stock Incentive Plan 1990 | Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 7		$ 8

[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 month periods ended August 31, 2014 and 2013 was $4 million for each respective period.