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INCOME TAXES - DEFERRED TAXES (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2023 | Dec. 31, 2022
Significant components of deferred tax assets |  |
Net operating loss carryforwards | $ 272,300 | $ 254,500
Federal and state tax credits | 64,700 | 56,700
Capitalized research and development | 43,300 | 21,800
Stock-based compensation | 11,200 | 10,800
Operating lease liabilities | 1,100 | 1,300
Other | 3,600 | 5,600
Total deferred tax assets | 396,200 | 350,700
Less: valuation allowance | (395,200) | (349,600)
Net deferred tax assets | 1,000 | 1,100
Operating leases, right-of-use assets | (1,000) | (1,100)
Total deferred tax liabilities | (1,000) | (1,100)
Valuation allowance |  |
Increase (decrease) in valuation allowance | $ 45,600 | $ 38,900

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