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Stock-Based Compensation - Weighted Average Assumptions Used to Estimate Fair Values (Detail) - USD ($)
$ / shares in Units, $ in Millions
6 Months Ended
Nov. 30, 2019
Nov. 30, 2018
Stock options    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Weighted average fair value per share of the options granted (in dollars per share) $ 18.46 $ 22.81
Dividend yield 1.00% 1.00%
Expected volatility 23.00% 26.60%
Weighted average expected life 6 years 6 years
Risk-free interest rate 1.50% 2.80%
Stock Incentive Plan | Stock options    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Unrecognized compensation costs from stock options $ 523  
Unrecognized compensation costs from stock options, net of estimated forfeitures, to be recognized as operating overhead expense over a weighted average period (in years) 2 years 10 months 24 days  
Class B Common Stock | Stock Incentive Plan    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Minimum term of market traded options for estimates of expected volatility 1 year