Consolidated Statements of Cash Flows $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (183,118)	$ (250,219)	$ (204,472)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	81,924	62,201	33,261
Depreciation and amortization expense	18,020	13,624	4,294
Impairment of other investments	5,000	36,447	0
Change in fair value of success payment liabilities	(5,130)	3,713	5,337
Gain on other investments	(2,923)	0	0
Lease expense, net of gain on lease remeasurement	(1,553)	911	3,181
Change in fair value of equity warrant	1,067	256	(1,323)
Net amortization and accretion on marketable securities	(930)	1,901	539
Loss (gain) on property and equipment disposals, net	103	1,210	(4,884)
Expense in connection with asset acquisition	0	0	3,529
Gain on net operating lease liability disposal	0	(308)	0
Changes in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	(1,968)	(6,987)	(1,388)
Accounts payable	667	91	(278)
Accrued liabilities and other current liabilities	(463)	4,542	6,120
Deferred revenue	(84,653)	(10,508)	(7,756)
Operating lease liabilities, non-current	4,855	13,202	2,966
Other non-current liabilities	(453)	3,675	0
Net cash used in operating activities	(169,555)	(126,249)	(160,874)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(24,276)	(65,504)	(51,481)
Purchases of marketable securities	(406,316)	(673,465)	(864,909)
Sales and maturities of marketable securities	419,052	617,396	686,322
Purchases of other investments	0	0	(43,448)
Net cash used in investing activities	(11,540)	(121,573)	(273,516)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercise of stock options	9,577	9,442	373
Proceeds from employee stock purchase plan	1,519	0	0
Taxes paid related to net share settlement of equity awards	(461)	0	0
Proceeds from initial public offering, net of issuance costs	0	391,802	0
Proceeds from issuance of convertible preferred stock, net of issuance costs	0	0	492,467
Payments for the repurchase of common stock	0	0	(11,806)
Payments for the repurchase of convertible preferred stock	0	0	(4,244)
Net cash provided by financing activities	10,635	401,244	476,790
Net (decrease) increase in cash, cash equivalents and restricted cash	(170,460)	153,422	42,400
Cash, cash equivalents and restricted cash at beginning of period	294,294	140,872	98,472
Cash, cash equivalents and restricted cash at end of period	123,834	294,294	140,872
Represented by:
Cash and cash equivalents	123,554	293,828	140,406
Restricted cash	280	466	466
Total	123,834	294,294	140,872
SUPPLEMENTAL CASH FLOW INFORMATION
Cash received for amounts related to tenant improvement allowances	4,761	13,295	2,966
Cash paid for amounts included in the measurement of lease liabilities	10,870	8,546	5,147
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	1,325	4,605	12,740
Remeasurement of operating lease right-of-use asset for lease modification	31	3,873	(8,958)
Acquisition of PACT Series D convertible preferred shares	2,923	0	0
Conversion of convertible preferred stock to common stock upon closing of initial public offering	0	1,010,968	0
Operating lease right-of-use assets obtained in exchange for lease obligations	0	0	30,475
Other investments received for sale of assets	$ 0	$ 0	$ 6,000