Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
OPERATING ACTIVITIES:
Net loss			$ (161,934)	$ (120,683)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation	$ 2,600	$ 1,400	4,853	2,646
Stock-based compensation expense			9,099	1,871
Change in the estimated fair value of contingent consideration			18,556	14,339
Change in the estimated fair value of success payment liabilities			32,469	38,481
Non-cash expense for operating lease right-of-use assets			2,838	1,790
Other non-cash items, net			(2,022)	493
Changes in operating assets and liabilities:
Prepaid expenses and other assets			(1,719)	423
Operating lease right-of-use assets and liabilities			3,386	91
Accounts payable			(373)	1,864
Accrued expenses and other liabilities			4,378	(4,228)
Net cash used in operating activities			(90,469)	(62,913)
INVESTING ACTIVITIES:
Purchases of marketable securities			(165,551)	(43,121)
Proceeds from sales and maturities of marketable securities			195,914	54,120
Purchases of property and equipment			(16,596)	(8,290)
Net cash provided by investing activities			13,767	2,709
FINANCING ACTIVITIES:
Proceeds from initial public offering of common stock, net of offering costs			626,405
Proceeds from issuance of convertible preferred stock, net of issuance costs				435,543
Proceeds from exercise of stock options			631	37
Net cash provided by financing activities			627,036	435,580
Net increase in cash, cash equivalents, and restricted cash			550,334	375,376
Cash, cash equivalents, and restricted cash at beginning of period			126,949	81,807	$ 81,807
Cash, cash equivalents, and restricted cash at end of period	$ 677,283	$ 457,183	677,283	457,183	$ 126,949
SUPPLEMENTAL CASH FLOW DISCLOSURES:
Tenant improvement allowance included in operating lease liabilities			4,935	3,745
Purchases of property and equipment included in accounts payable and accrued liabilities			3,414	2,289
Cash received from lessor for tenant improvement allowance			$ 3,386	91
Right-of-use assets obtained in exchange for operating lease liabilities				$ 19,971