Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net loss	$ (113,837)	$ (86,075)
Adjustments to reconcile net loss to net cash used in operating activities:
Share-based compensation expense	16,856	14,461
Depreciation and amortization expense	2,637	1,756
Accretion of discount and amortization of premium on investments, net	(818)	3,237
Non-cash lease expense	3,935	367
Realized loss on investments	490
Others		(30)
Changes in operating assets and liabilities:
Prepaid expenses and other assets	(1,489)	(4,435)
Operating lease liabilities	32,469
Accounts payable and accrued and other liabilities	2,757	2,792
Net cash used in operating activities	(57,000)	(67,927)
Cash flows from investing activities:
Purchases of available-for-sale securities	(385,887)	(227,282)
Proceeds from maturities of available-for-sale securities	248,309	264,841
Purchase of property and equipment	(47,111)	(5,025)
Net cash provided by (used in) investing activities	(184,689)	32,534
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	445
Proceeds from stock option exercises	1,397	1,479
Payments of deferred offering costs		(277)
Net cash provided by financing activities	219,012	1,202
Net decrease in cash and cash equivalents	(22,677)	(34,191)
Cash, cash equivalents and restricted cash at beginning of year	62,914	97,105
Cash, cash equivalents and restricted cash at end of year	40,237	62,914
Reconciliation of cash, cash equivalents and restricted cash to the balance sheets:
Cash and cash equivalents	37,494	60,816
Restricted cash	2,743	2,098
Total cash, cash equivalents and restricted cash	40,237	62,914
Supplemental disclosures of non-cash investing and financing activities:
Acquisitions of property and equipment in accounts payable	$ 4,579	$ 238