SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - STOCK OPTIONS AND EMPLOYEE STOCK PURCHASE PLAN (Details)	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Stock Options
Stock-Based Compensation
Vesting period of awards	4 years
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)	0.00%	0.00%
Expected volatility range, minimum (as a percent)	81.50%	77.70%
Expected volatility range, maximum (as a percent)	82.10%	81.60%
Risk-free interest rate range, minimum (as a percent)	3.42%	1.69%
Risk-free interest rate range, maximum (as a percent)	4.62%	3.77%
Expected term	6 years	5 years 6 months
Employee Stock Purchase Plan
Assumptions used to estimate fair value of awards
Dividend yield (as a percent)	0.00%	0.00%
Expected volatility range, minimum (as a percent)	79.00%	61.40%
Expected volatility range, maximum (as a percent)	83.20%	86.50%
Risk-free interest rate range, minimum (as a percent)	4.73%	0.40%
Risk-free interest rate range, maximum (as a percent)	5.40%	2.79%
Employee Stock Purchase Plan | Minimum
Assumptions used to estimate fair value of awards
Expected term	6 months	6 months
Employee Stock Purchase Plan | Maximum
Assumptions used to estimate fair value of awards
Expected term	12 months	12 months