Common Stock and Stock-Based Compensation - Total Stock-Based Compensation Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	May 31, 2018	May 31, 2017	May 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 218	$ 215	$ 236
Accelerated stock option expense	18	14	30
Class B Common Stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	218	215	236
Class B Common Stock | Stock options
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	149	145	171
Class B Common Stock | ESPPs
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	34	36	31
Class B Common Stock | Restricted stock
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based compensation expense	$ 35	$ 34	$ 34