Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 1,198,768	$ 327,214
Marketable securities	350,614	779,246
Prepaid expenses	39,358	32,888
Receivables and other current assets	24,705	12,826
Total current assets	1,613,445	1,152,174
Marketable securities	49,411	131,506
Property, plant and equipment, net	155,376	151,176
Intangible assets, net	12,183	14,326
Goodwill	13,128	13,128
Operating lease right-of-use assets	189,464	185,885
Restricted cash and other non-current assets	74,783	79,229
Total assets	2,107,790	1,727,424
Current liabilities:
Accounts payable	26,181	42,995
Accrued expenses and other current liabilities	135,612	141,556
Operating lease liability, current portion	20,955	20,175
Deferred revenue, current portion	3,915	8,474
Collaboration research advancement, current portion	10,518	10,380
Total current liabilities	197,181	223,580
Deferred revenue, net of current portion	25,762	9,791
Collaboration research advancement, net of current portion	23,917	27,834
Operating lease liability, net of current portion	174,564	170,812
Other non-current liabilities	4,335	10,414
Total liabilities	425,759	442,431
Commitments and contingencies (Note 8)
Stockholders’ equity:
Preferred stock, $0.01 par value, 5,000 shares authorized; 0 shares issued and outstanding at June 30, 2020 and December 31, 2019	0	0
Common stock, $0.01 par value, 125,000 shares authorized; 66,196 and 55,368 shares issued and outstanding at June 30, 2020 and December 31, 2019, respectively	662	554
Additional paid-in capital	4,189,697	3,568,184
Accumulated other comprehensive loss	(2,400)	(1,893)
Accumulated deficit	(2,505,928)	(2,281,852)
Total stockholders’ equity	1,682,031	1,284,993
Total liabilities and stockholders’ equity	$ 2,107,790	$ 1,727,424