Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flows from operating activities:
Net loss	$ (363,872)	$ (52,412)	$ (75,305)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	48,454	31,960	4,456
Depreciation expense	3,925	3,549	2,845
Net amortization of premiums and discounts on investments	2,052	(416)	(2,495)
Acquired in-process research and development	123,000
Loss on initial consolidation of variable interest entity	11,855
Change in fair value of contingent consideration liability	2,836
Loss on sale of equipment			56
Changes in assets and liabilities:
Prepaid expenses and other current assets	(2,681)	(4,665)	(2,123)
Operating lease assets and liabilities, net	277	571	1,233
Accounts payable	930	(410)	3,000
Accrued expenses and other liabilities	6,002	2,010	2,200
Accounts receivable	74,677	(75,000)
Contract asset	3,117	(7,654)
Other liabilities	15,000
Other assets	22	(22)
Net cash used in operating activities	(74,406)	(102,489)	(66,133)
Cash flows from investing activities:
Purchases of property and equipment	(3,471)	(1,931)	(8,002)
Proceeds from sale of equipment			20
Purchases of investments	(980,665)	(266,455)	(553,517)
Proceeds from maturities of investments	529,923	350,058	242,475
Cash paid for acquisition of ZebiAI, net of cash acquired	(25,298)
Net cash provided by (used in) investing activities	(479,511)	81,672	(319,024)
Cash flows from financing activities:
Proceeds from issuance of convertible preferred stock, net of issuance costs			4,993
Proceeds from issuance of common stock upon exercise of stock options	4,739	1,216	613
Proceeds from issuance of common stock upon initial public offering, net		425,293
Proceeds from issuance of common stock upon follow-on offering, net	382,210
Proceeds from issuance of common stock under ESPP	1,141
Net cash provided by financing activities	388,090	426,509	5,606
Net (decrease) increase in cash, cash equivalents and restricted cash	(165,827)	405,692	(379,551)
Cash, cash equivalents and restricted cash at beginning of period	448,524	42,832	422,383
Cash, cash equivalents and restricted cash at end of period	282,697	448,524	42,832
Supplemental disclosure of non-cash investing and financing activities:
Property and equipment additions included in accounts payable and accrued expenses	1,010	519	745
Reclassification of restricted stock liability to additional paid-in capital	3	153	400
Assets obtained in asset acquisition	662
Liabilities assumed in asset acquisition	2,330
Fair value of equity issued in connection with asset acquisition	$ 62,990
Extinguishment upon modification of Series C preferred stock		(177,789)
Conversion of preferred stock into common stock upon initial public offering		715,508
Right of use asset obtained in exchange for lease obligation		$ 819	$ 24,936