Condensed Consolidated Balance Sheets (unaudited) - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 353,468	$ 317,705
Marketable securities	486,233	833,546
Prepaid expenses	33,726	37,472
Receivables and other current assets	16,597	16,116
Inventory	13,502	10,698
Total current assets	903,526	1,215,537
Marketable securities	101,927	122,891
Property, plant and equipment, net	158,820	162,831
Intangible assets, net	16,263	10,041
Goodwill	13,128	13,128
Operating lease right-of-use assets	190,993	184,019
Restricted cash and other non-current assets	69,802	72,805
Total assets	1,454,459	1,781,252
Current liabilities:
Accounts payable	39,294	21,602
Accrued expenses and other current liabilities	168,035	145,406
Operating lease liability, current portion	28,669	25,024
Deferred revenue, current portion	2,687	2,320
Collaboration research advancement, current portion	9,080	9,236
Total current liabilities	247,765	203,588
Deferred revenue, net of current portion	25,762	25,762
Collaboration research advancement, net of current portion	18,547	21,581
Operating lease liability, net of current portion	169,933	167,997
Other non-current liabilities	7,891	7,268
Total liabilities	469,898	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 June 30, 2021 and December 31, 2020	0	0
Common stock, $0.01 par value, 125,000 shares authorized; 67,551 and 66,432 shares issued and outstanding at June 30, 2021 and December 31, 2020, respectively	676	665
Additional paid-in capital	4,337,719	4,260,443
Accumulated other comprehensive loss	(5,777)	(5,505)
Accumulated deficit	(3,348,057)	(2,900,547)
Total stockholders’ equity	984,561	1,355,056
Total liabilities and stockholders’ equity	$ 1,454,459	$ 1,781,252