Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (181,702)	$ (174,721)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	38,621	63,561
Depreciation and amortization expense	15,193	12,979
Impairment of other investments	12,923	5,000
Net amortization and accretion on marketable securities	(6,212)	278
Change in fair value of success payment liabilities	(3,309)	2,177
Non-cash lease income	(1,344)	(1,104)
Loss on property and equipment disposals, net	1,072	97
Change in fair value of equity warrant	0	1,067
Changes in operating assets and liabilities:
Prepaid expenses, other current assets and other assets	(23)	(672)
Accounts payable	1,039	1,193
Accrued liabilities and other current liabilities	1,020	(5,836)
Deferred revenue	0	(36,299)
Operating lease liabilities, non-current	0	3,331
Other non-current liabilities	(337)	(339)
Net cash used in operating activities	(123,059)	(129,288)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchases of property and equipment	(2,661)	(19,694)
Purchases of marketable securities	(220,095)	(346,647)
Sales and maturities of marketable securities	507,494	308,153
Net cash provided by (used in) investing activities	284,738	(58,188)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from exercise of stock options	155	9,252
Proceeds from employee stock purchase plan	1,163	887
Taxes paid related to net share settlement of equity awards	(334)	(367)
Net cash provided by financing activities	984	9,772
Net increase (decrease) in cash, cash equivalents and restricted cash	162,663	(177,704)
Cash, cash equivalents and restricted cash at beginning of period	123,834	294,294
Cash, cash equivalents and restricted cash at end of period	286,497	116,590
Represented by:
Cash and cash equivalents	286,214	116,311
Restricted cash	283	279
Total	286,497	116,590
SUPPLEMENTAL CASH FLOW INFORMATION
Cash paid for amounts included in the measurement of lease liabilities	8,030	8,136
Cash received for amounts related to tenant improvement allowances	0	3,238
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable and accrued liabilities	$ 2	$ 3,563