Common Stock and Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	3 Months Ended
	Aug. 31, 2016	Aug. 31, 2015
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 57	$ 54
Class B Common Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	57	54
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	39	39
Accelerated stock option expense	5	6
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
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	$ 9	$ 7