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Stock-Based Compensation Plans - Estimated Fair Value of Stock Options (Detail) - Stock Options [Member] - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Dividend yield 2.40% 2.40% 2.20%
Volatility 23.30% 25.40% 29.60%
Risk-free interest rate 2.50% 2.90% 1.80%
Expected life 5 years 4 months 24 days 5 years 4 months 24 days 5 years 7 months 6 days
Weighted average grant date fair value $ 4.35 $ 5.08 $ 5.17