XML 77 R66.htm IDEA: XBRL DOCUMENT v3.20.2
Stock-Based Compensation - Fair Value of Each Option Grant Weighted Average Assumptions (Detail)
9 Months Ended
Sep. 30, 2020
Sep. 30, 2019
Share-based Payment Arrangement [Abstract]    
Dividend yield (as a percent) 0.60% 0.66%
Risk-free interest rate (as a percent) 1.53% 2.60%
Stock price volatility (as a percent) 28.10% 25.80%
Expected life (years) 5 years 5 years