CONSOLIDATED STATEMENTS OF CASH FLOWS $ in Thousands	12 Months Ended
	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Operating activities:
Net loss	$ (581,784)	$ (357,937)	$ (213,256)
Non-cash adjustments reconciling net loss to operating cash flows
Non-cash consideration earned from license agreement	0	(11,424)	0
Change in fair value of long-term investment	7,411	(4,205)	0
Depreciation of property and equipment	1,781	641	249
Amortization of premium and accretion of discounts on investments	4,702	(674)	(3,421)
Share-based compensation expense	113,502	85,847	55,537
Changes in operating assets and liabilities:
Other current assets	(3,107)	(4,180)	(5,487)
Other long-term assets	(9,892)	(3,424)	(4,375)
Right-of-use asset	2,210	582	0
Lease liability	5,315	(652)	0
Accounts payable, accrued liabilities, deferred revenue and other liabilities	71,062	23,895	23,027
Cash flows used in operating activities	(388,800)	(271,531)	(147,726)
Investing activities:
Purchases of short-term investments	(1,422,729)	(662,824)	(530,228)
Sales and maturities of short-term investments	843,623	527,334	355,640
Purchases of property and equipment	(9,795)	(4,367)	(1,552)
Cash flows used in investing activities	(588,901)	(139,857)	(176,140)
Financing activities:
Proceeds from issuance of common stock, net of issuance costs	474,697	1,203,617	327,830
Proceeds from issuance of common stock under equity incentive plans	27,958	45,891	8,473
Proceeds from disgorgement of shareholders’ short-swing profits	0	0	1,050
Proceeds from issuances under ESPP	2,567	1,206	675
Cash flows provided by financing activities	505,222	1,250,714	338,028
(Decrease) increase in cash, cash equivalents and restricted cash	(472,479)	839,326	14,162
Cash, cash equivalents and restricted cash, beginning of year	886,182	46,856	32,694
Cash, cash equivalents and restricted cash, end of year	413,703	886,182	46,856
Reconciliation of cash, cash equivalents and restricted cash, end of year:
Cash and cash equivalents	413,083	885,562	46,535
Restricted cash included in other long-term assets	620	620	321
Total cash, cash equivalents and restricted cash	413,703	886,182	46,856
Supplemental disclosures of non-cash investing activities:
Accrued capital expenditures	583	292	0
Allowance utilized for tenant improvements	0	2,015	0
Initial recognition of operating right-of-use asset	0	39,890	0
Initial recognition of operating lease liability	$ 0	$ 41,905	$ 0