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STOCK-BASED COMPENSATION - Schedule of Weighted-Average Assumptions for Options and ESPP Subscriptions Granted Granted (Details) - $ / shares
3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Option Awards    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Average risk-free interest rate 1.40% 2.50%
Expected dividend yield 0.00% 0.00%
Expected volatility (as a percent) 29.70% 29.20%
Expected term 5 years 2 months 12 days 5 years 2 months 12 days
Fair value, per option (in dollars per share) $ 68.36 $ 54.03
ESPP    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Average risk-free interest rate 1.60% 2.40%
Expected dividend yield 0.00% 0.00%
Expected volatility (as a percent) 31.90% 25.30%
Expected term 7 months 6 days 7 months 6 days
Fair value, per option (in dollars per share) $ 47.14 $ 48.83