Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Cash flows from operating activities:
Net loss	$ (117,501)	$ (113,837)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	17,199	16,856
Depreciation and amortization expense	5,869	2,637
Accretion of discount and amortization of premium on investments, net	(8,940)	(818)
Non-cash lease expense	2,222	3,935
Realized (gain) loss on investments	(34)	490
Impairment of right-of-use assets	4,100
Changes in operating assets and liabilities:
Prepaid expenses and other assets	1,716	(1,489)
Operating lease liabilities	4,986	32,469
Accounts payable and accrued and other liabilities	4,223	2,757
Net cash used in operating activities	(86,160)	(57,000)
Cash flows from investing activities:
Purchases of investments	(260,233)	(385,887)
Proceeds from sales and maturities of investments	(367,395)	(248,309)
Purchase of property and equipment	(28,147)	(47,111)
Net cash provided by (used in) investing activities	79,015	(184,689)
Cash flows from financing activities:
Proceeds from secondary offering, net of issuance costs		215,611
Proceeds from ATM offering, net of issuance costs		1,559
Proceeds from ESPP purchases	530	445
Proceeds from stock option exercises	161	1,397
Net cash provided by financing activities	691	219,012
Net decrease in cash and cash equivalents	(6,454)	(22,677)
Cash, cash equivalents and restricted cash at beginning of year	40,237	62,914
Cash, cash equivalents and restricted cash at end of year	33,783	40,237
Reconciliation of cash, cash equivalents and restricted cash to the balance sheets:
Cash and cash equivalents	31,040	37,494
Restricted cash	2,743	2,743
Total cash, cash equivalents and restricted cash	33,783	40,237
Supplemental disclosures of non-cash investing activities:
Acquisitions of property and equipment recorded in accounts payable and accrued and other current liabilities	$ 268	$ 4,579