Annual report pursuant to Section 13 and 15(d)

Stock-Based Compensation Plans (Weighted-Average Assumptions) (Details)

v3.19.2
Stock-Based Compensation Plans (Weighted-Average Assumptions) (Details) - $ / shares
12 Months Ended
May 31, 2019
May 31, 2018
May 31, 2017
Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate 2.90% 2.10% 1.20%
Dividend yield 3.50% 3.40% 3.60%
Volatility factor 0.18% 0.17% 0.18%
Expected option life in years 6 years 1 month 6 days 6 years 1 month 6 days 6 years 1 month 6 days
Weighted-average grant-date fair value of stock options granted (per share) $ 8.87 $ 6.47 $ 5.74
Performance Stock Options [Member]      
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Risk-free interest rate 2.90% 2.40% 1.30%
Dividend yield 3.50% 3.30% 3.60%
Volatility factor 0.18% 0.18% 0.18%
Expected option life in years 6 years 6 months 6 years 6 months 6 years 6 months
Weighted-average grant-date fair value of stock options granted (per share) $ 9.02 $ 7.45 $ 5.97