Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (81,212)	$ (111,903)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation	16,805	27,527
Depreciation and amortization	1,567	2,735
Noncash operating lease expense	1,347	1,222
Accretion of discount on short-term investments, net	(2,057)	0
Impairment of long-lived assets	1,335	0
Other adjustments	3	(8)
Changes in operating assets and liabilities:
Accounts receivable	1,146	(202)
Prepaid expenses and other current assets	(3,194)	(422)
Other assets	1,041	(758)
Accounts payable	(3,046)	227
Amounts due to joint development partners	(1,400)	454
Accrued expenses and other current liabilities	(18,201)	(18,286)
Operating lease liabilities	(1,819)	(1,642)
Other liabilities	5	426
Net cash used in operating activities	(87,680)	(100,630)
Cash flows from investing activities:
Purchases of short-term investments	(38,998)	0
Proceeds from maturities of short-term investments	21,558	0
Purchases of property and equipment	(680)	(1,356)
Proceeds from disposal of property and equipment	0	19
Purchases of intangible assets	0	(40)
Net cash used in investing activities	(18,120)	(1,377)
Cash flows from financing activities:
Proceeds from the issuance of common stock under the Employee Stock Purchase Plan	0	1,292
Proceeds from exercised stock options	0	871
Principal payments on finance lease obligations	(217)	(293)
Principal payments on loans	(410)	(358)
Net cash provided by (used in) financing activities	(627)	1,512
Effect of exchange rate changes on cash, cash equivalents, and restricted cash	924	155
Net decrease in cash, cash equivalents, and restricted cash	(105,503)	(100,340)
Cash, cash equivalents, and restricted cash - beginning of period	617,465	1,339,092
Cash, cash equivalents, and restricted cash - end of period	511,962	1,238,752
Reconciliation of cash, cash equivalents, and restricted cash to the condensed consolidated balance sheets:
Cash and cash equivalents	510,008	1,237,246
Restricted cash included in prepaid expenses and other current assets	1,954	1,506
Total cash, cash equivalents, and restricted cash	511,962	1,238,752
Supplemental disclosure of cash flow information:
Cash paid for interest	158	281
Supplemental schedule of non-cash investing and financing activities:
Acquisitions of property and equipment included in liabilities	197	1,038
Right-of-use assets obtained in exchange for operating lease obligations	0	44,549
Right-of-use assets obtained in exchange for finance lease obligations	0	5,240
Vesting of early exercised stock options	$ 0	$ 21