STOCK-BASED COMPENSATION - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 2,017	$ 1,969	$ 4,085	$ 3,343
ACM Shanghai
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	2,017	1,969	69	175
Employee Stock Option Plan
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	1,975	1,872	3,993	3,145
Employee Stock Option Plan | ACM Shanghai
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	30	85	69	175
Non-Employee Stock Option Plan
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	12	12	23	23
Cost of revenue
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	125	140	250	253
Sales and marketing expense
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	431	574	862	928
Research and development expense
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	709	656	1,410	1,067
General and administrative expense
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 752	$ 599	$ 1,563	$ 1,095