Common Stock and Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Feb. 29, 2016	Feb. 28, 2015	Feb. 29, 2016	Feb. 28, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense				$ 176	$ 140
Class B Common Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 60	$ 48	176	140
Class B Common Stock | Stock Incentive Plan | Employee Stock Option
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	[1]	44	35	128	100
Accelerated stock option expense		8	5	22	14
Class B Common Stock | Stock Incentive Plan | Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		9	8	26	23
Class B Common Stock | Employee Stock Purchase Plans | Employee Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense		$ 7	$ 5	$ 22	$ 17

[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 $8 million and $5 million for the three month periods ended February 29, 2016 and February 28, 2015, respectively, and $22 million and $14 million for the nine month periods ended February 29, 2016 and February 28, 2015, respectively.