LICENSE, COLLABORATION AND OTHER REVENUE - MTPC Collaboration Agreement - Narrative (Details)		3 Months Ended
	Dec. 11, 2015 USD ($) performance_obligation	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues		$ 32,607,000	$ 40,005,000
Deferred revenue		43,991,000
Payables		11,882,000		$ 14,635,000
Revenue recognized		0	3,738,000
Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable		2,692,000	417,000	$ 3,333,000	$ 1,901,000
Mitsubishi Tanabe Pharma Corporation
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues	$ 5,400,000
Deferred revenue		695,000
Payables		0
Mitsubishi Tanabe Pharma Corporation | License Collaboration And Other Revenue, Royalties
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Total revenues		400,000	400,000
Mitsubishi Tanabe Pharma Corporation | Regulatory Milestone Payments
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Milestone revenue	$ 25,000,000	25,000,000
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Collaboration Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Number of performance obligations | performance_obligation	2
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Upfront cash payment received	$ 20,000,000
Cost of research services	20,500,000
Milestone revenue	$ 10,000,000
Deferred revenue		0
Accounts receivable		400,000
Mitsubishi Tanabe Pharma Corporation | Development And Commercialize Research And License Agreement | Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable		0
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Deferred revenue		700,000
Revenue recognized		0	$ 3,700,000
Other liabilities, current		0
Mitsubishi Tanabe Pharma Corporation | Mitsubishi Tanabe Pharma Corporation Supply Agreement | Accounts receivable
Collaborative Arrangement and Arrangement Other than Collaborative [Line Items]
Accounts receivable		$ 700,000