RESTRUCTURING CHARGES - Narrative (Details)				3 Months Ended			9 Months Ended
	Mar. 01, 2024 employee	Nov. 01, 2023 employee	Apr. 26, 2023 USD ($) employee	Sep. 30, 2024 USD ($)	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)	Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Jun. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges							$ 603,000
April 2023 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Number of employees eliminated in restructuring | employee			110
Restructuring expected cost			$ 5,000,000
Restructuring charges				$ 0			0	$ 5,000,000
April 2023 Restructuring Plan | Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring charges								3,800,000
April 2023 Restructuring Plan | General and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring charges								$ 1,200,000
November 2023 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Number of employees eliminated in restructuring | employee		162
Restructuring charges						$ 6,700,000
Percentage of positions eliminated in restructuring		40.00%
November 2023 Restructuring Plan | Minimum
Restructuring Cost and Reserve [Line Items]
Restructuring expected cost				8,000,000.0			8,000,000.0
November 2023 Restructuring Plan | Minimum | Forecast
Restructuring Cost and Reserve [Line Items]
Expected cost remaining									$ 900,000
November 2023 Restructuring Plan | Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring expected cost				9,000,000.0			9,000,000.0
November 2023 Restructuring Plan | Maximum | Forecast
Restructuring Cost and Reserve [Line Items]
Expected cost remaining									$ 1,900,000
November 2023 Restructuring Plan | Full-Time Employees
Restructuring Cost and Reserve [Line Items]
Number of employees eliminated in restructuring | employee		108
November 2023 Restructuring Plan | Contracted Employees
Restructuring Cost and Reserve [Line Items]
Number of employees eliminated in restructuring | employee		54
France Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Number of employees eliminated in restructuring | employee	93
Restructuring charges						$ 4,700,000
Percentage of positions eliminated in restructuring	24.00%
Restructuring costs incurred				2,200,000	$ 2,400,000
France Restructuring Plan | Minimum
Restructuring Cost and Reserve [Line Items]
Restructuring expected cost				5,300,000			5,300,000
France Restructuring Plan | Minimum | Forecast
Restructuring Cost and Reserve [Line Items]
Expected cost remaining										$ 200,000
France Restructuring Plan | Maximum
Restructuring Cost and Reserve [Line Items]
Restructuring expected cost				$ 5,600,000			$ 5,600,000
France Restructuring Plan | Maximum | Forecast
Restructuring Cost and Reserve [Line Items]
Expected cost remaining										$ 500,000