INCOME TAXES - Schedule of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Net operating loss carryforwards	$ 196,719	$ 174,129
Research and development tax credit carryforwards	54,336	44,264
Stock-based compensation	5,983	7,695
Deferred revenue	0	38,700
Capitalized research	71,675	37,985
Fixed assets	17,152	10,087
Intangible assets	101	0
Lease liability	8,559	10,074
Accruals and reserves	2,409	1,603
Other	259	283
Total deferred tax asset	357,193	324,820
Valuation allowance	351,430	301,840
Deferred tax assets	5,763	22,980
Liabilities:
Intangible assets	0	(13,512)
Operating lease right-of-use assets	(5,763)	(14,620)
Deferred tax liabilities	(5,763)	(28,132)
Total net deferred tax liabilities	$ 0	$ (5,152)