v3.19.3.a.u2
Incentive Stock Program - Options Fair Value (Details) - Stock options - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Incentive Stock Programs      
Fair value of an option granted (in dollars per share) $ 14.50 $ 10.93 $ 6.54
Fair value assumptions:      
Risk-free interest rate (as a percent) 2.50% 2.70% 2.10%
Average life of options (years) 6 years 6 years 6 years
Volatility (as a percent) 19.80% 19.00% 18.00%
Dividend yield (as a percent) 1.70% 1.90% 2.40%