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Stock-Based Compensation - Assumptions Used in Valuation and Weighted Average Fair Value of Stock Option Grants (Details) - $ / shares
3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Share-based Payment Arrangement [Abstract]    
Weighted average fair value of grants (in dollars per share) $ 23.97 $ 17.70
Risk-free interest rate 0.41% 1.44%
Expected volatility 48.49% 43.95%
Expected life in years 4 years 7 months 13 days 4 years 7 months 2 days