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Stock-Based Compensation - Weighted-Average Assumptions (Details) - $ / shares
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Share-based Payment Arrangement [Abstract]      
Weighted average fair value (in dollars per share) $ 68.05 $ 57.75 $ 40.87
Risk-free interest rate 2.37% 2.65% 2.03%
Average expected option life 5 years 5 months 1 day 5 years 3 months 25 days 5 years 3 months 3 days
Expected volatility 19.22% 18.05% 18.74%
Expected dividend yield 0.58% 0.59% 0.67%