Common Stock and Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Nov. 30, 2017	Nov. 30, 2016	Nov. 30, 2017	Nov. 30, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense			$ 103	$ 111
Class B Common Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 53	$ 54	103	111
Class B Common Stock | Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	39	36	72	75
Accelerated stock option expense	5	3	8	8
Class B Common Stock | ESPPs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	9	11	17	20
Class B Common Stock | Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 5	$ 7	$ 14	$ 16