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STOCK-BASED COMPENSATION - Restricted stock activity (Details) - USD ($)
 1 Months Ended 12 Months Ended
May 31, 2018
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Employee Stock Purchase Plan        
Compensation expense   $ 33,900,000 $ 30,700,000 $ 26,600,000
ESPP        
Employee Stock Purchase Plan        
Number of shares of common stock made available for purchase to employees 750,000      
Maximum percentage of annual salary that an employee is permitted to utilize to purchase stock 10.00%      
Maximum number of shares that a participant can purchase during any single offering period 312      
Maximum fair market value of stock an employee can purchase under the plan per calendar year $ 25,000      
Exercise price per share of common stock as a percent of fair market value   85.00%    
Compensation expense   $ 2,700,000 $ 600,000 $ 400,000
Shares reserved for future issuance   552,734    
RSAs and RSUs        
Number of shares        
Beginning balance (in shares)   556,062 443,319 342,082
Granted (in shares)   401,685 369,037 298,084
Vested (in shares)   (237,315) (201,457) (166,598)
Forfeited (in shares)   (82,251) (54,837) (30,249)
Ending balance of Outstanding and exercisable (in shares)   638,181 556,062 443,319
Weighted average grant date fair value        
Beginning balance (in USD per share)   $ 112.07 $ 99.22 $ 108.40
Granted (in dollars per share)   132.58 119.97 92.32
Vested (in USD per share)   108.25 99.87 106.13
Forfeited (in USD per share)   121.02 106.07 97.01
Ending balance of Outstanding and exercisable (in USD per share)   $ 125.25 $ 112.07 $ 99.22
Restricted Stock        
Number of shares        
Vested (in shares)   (219,527)    
RSAs        
Number of shares        
Ending balance of Outstanding and exercisable (in shares)   0    
PSUs        
Number of shares        
Beginning balance (in shares)   166,702 152,410 122,666
Granted (in shares)   87,146 64,668 71,302
Vested (in shares)   (55,399) (16,834) (29,468)
Forfeited (in shares)   (63,965) (33,542) (12,090)
Ending balance of Outstanding and exercisable (in shares)   134,484 166,702 152,410
Weighted average grant date fair value        
Beginning balance (in USD per share)   $ 125.08 $ 108.41 $ 115.18
Granted (in dollars per share)   144.35 141.41 98.32
Vested (in USD per share)   130.05 96.00 111.45
Forfeited (in USD per share)   141.49 95.40 110.20
Ending balance of Outstanding and exercisable (in USD per share)   $ 127.72 $ 125.08 $ 108.41