Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (360,779)	$ (186,655)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	5,541	5,011
Gain on disposal of property and equipment	(162)	0
Equity-based compensation	66,774	32,448
Amortization of investment premiums	5,252	4,970
Loss from equity method investment	7,831	0
Deferral of equity method investment intra-entity profit on sales	8,530	0
Change in fair value of contingent consideration	8,059	0
In-process research and development charge	55,990	0
Changes in operating assets and liabilities:
Accounts receivable	(1,992)	(361)
Prepaid expenses and other current assets	(228)	(5,073)
Operating lease right-of-use assets	8,516	6,761
Other assets	(982)	(248)
Accounts payable	(5,334)	(1,870)
Accrued expenses	12,852	(1,170)
Deferred revenue	(46,739)	(16,986)
Operating lease liabilities	(6,547)	(7,206)
Net cash used in operating activities	(243,418)	(170,379)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchases of property and equipment	(9,646)	(9,888)
Purchases of marketable securities	(192,598)	(772,759)
Maturities of marketable securities	437,387	390,984
Proceeds from sale of property and equipment	150	0
Acquired in-process research and development, net of cash acquired of $287	(44,832)	0
Net cash provided by (used in) investing activities	190,461	(391,663)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from options exercised	13,984	39,868
Issuance of shares through employee stock purchase plan	1,068	970
Net cash provided by financing activities	77,192	734,408
Net increase in cash and cash equivalents and restricted cash equivalents	24,235	172,366
Cash and cash equivalents and restricted cash equivalents, beginning of period	125,486	164,606
Cash and cash equivalents and restricted cash equivalents, end of period	149,721	336,972
Reconciliation of cash and cash equivalents and restricted cash equivalents to condensed consolidated balance sheet:
Cash and cash equivalents	141,194	334,736
Restricted cash equivalents, included in investments and other assets	8,527	2,236
Total cash and cash equivalents and restricted cash equivalents	149,721	336,972
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Purchases of property and equipment unpaid at period end	2,180	633
Right-of-use asset acquired under operating lease	30,663	49,435
Contingent consideration liability assumed in asset acquisition	10,541	0
Proceeds from at-the-market offerings unpaid at period end	8,255	0
Non-cash trade-in of property and equipment	200	0
AvenCell [Member]
Adjustments to reconcile net loss to net cash used in operating activities:
Loss from equity method investment	(8,500)
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Non-cash contribution of intellectual property to AvenCell Therapeutics, Inc.	0	62,900
Follow-on Offering [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	0	648,315
At The Market Offerings [Member]
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of common stock	$ 62,140	$ 45,255