STOCK-BASED COMPENSATION, Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 5,117	$ 5,628	$ 3,572
Employee Stock Purchase Plan [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	4,674	4,900	2,265
Employee Stock Purchase Plan [Member] | ACM Shanghai [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	349	332	0
Non-Employee Stock Purchase Plan [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	94	396	1,307
Cost of Revenue [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	397	175	250
Sales and Marketing Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	1,802	1,199	328
Research and Development Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	1,115	763	1,093
General and Administrative Expense [Member]
Stock-based Compensation Expense [Abstract]
Stock-based compensation expense	$ 1,803	$ 3,491	$ 1,901