STOCK-BASED COMPENSATION - Narrative (Details) - shares	3 Months Ended	6 Months Ended
	Jun. 30, 2026	Jun. 30, 2026
ACM Shanghai 2023 Stock Option Plan
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Options granted (in shares)	0	0
Share-Based Payment Arrangement, Employee
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Options granted (in shares)		57,800
Share-Based Payment Arrangement, Nonemployee
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Options granted (in shares)	0	0
Employee Share Option | Share-Based Payment Arrangement, Employee
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Cost not yet recognized (in years)		4 years
Restricted Stock Units (RSUs) | Share-Based Payment Arrangement, Employee
Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]
Equity instruments other than options granted (in shares)		6,208