Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 402,461	$ 317,705
Marketable securities	375,140	833,546
Prepaid expenses	30,712	37,472
Receivables and other current assets	23,246	16,116
Inventory	766	10,698
Total current assets	832,325	1,215,537
Marketable securities	193,129	122,891
Property, plant and equipment, net	45,745	162,831
Intangible assets, net	11,009	10,041
Goodwill	12,056	13,128
Operating lease right-of-use assets	174,435	184,019
Restricted cash and other non-current assets	70,945	72,805
Total assets	1,339,644	1,781,252
Current liabilities:
Accounts payable	21,668	21,602
Accrued expenses and other current liabilities	203,790	145,406
Operating lease liability, current portion	29,441	25,024
Deferred revenue, current portion	2,530	2,320
Collaboration research advancement, current portion	9,130	9,236
Total current liabilities	266,559	203,588
Deferred revenue, net of current portion	25,761	25,762
Collaboration research advancement, net of current portion	16,767	21,581
Operating lease liability, net of current portion	152,126	167,997
Other non-current liabilities	7,904	7,268
Total liabilities	469,117	426,196
Commitments and contingencies (Note 9)
Stockholders’ equity:
Preferred stock, $0.01 par value, 5,000 shares authorized; 0 shares issued and outstanding at September 30, 2021 and December 31, 2020	0	0
Common stock, $0.01 par value, 125,000 shares authorized; 70,097 and 66,432 shares issued and outstanding at September 30, 2021 and December 31, 2020, respectively	701	665
Additional paid-in capital	4,440,605	4,260,443
Accumulated other comprehensive loss	(5,906)	(5,505)
Accumulated deficit	(3,564,873)	(2,900,547)
Total stockholders’ equity	870,527	1,355,056
Total liabilities and stockholders’ equity	$ 1,339,644	$ 1,781,252