Income Taxes - Summary of deferred tax assets and liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Gross deferred tax assets
Net operating loss carryforwards	$ 188,255	$ 183,711
Tax credit carryforwards	50,688	47,927
Deferred research and development expenses	67,494	59,753
Stock-based compensation	9,993	14,719
Fixed assets	1,193	1,287
Accrued expenses and other	373	370
Deferred tax assets, gross	317,996	307,767
Gross deferred tax liabilities
IPR&D intangibles	(6,840)	(6,840)
Total deferred tax assets and liabilities	311,156	300,927
Valuation allowance	(312,769)	(302,540)
Net deferred tax liability	$ (1,613)	$ (1,613)