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Share-Based Compensation - Fair Value of Options Granted (Details)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions and Methodology [Abstract]    
Dividend yields 2.39% 1.99%
Volatility factors of expected market price of common stock 28.67% 28.60%
Risk-free interest rates 2.61% 2.85%
Expected life of options 8 years 8 years