Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 232,850	$ 238,183
Marketable securities	182,143	218,957
Accounts receivable	1,832	418
Prepaid expenses and other current assets	8,281	6,286
Total current assets	425,106	463,844
Property and equipment, net	12,218	10,887
Right-of-use assets	27,022	28,761
Restricted cash and other non-current assets	2,391	5,393
Total assets	466,737	508,885
Current liabilities:
Accounts payable	10,394	5,843
Accrued expenses	8,669	22,120
Deferred revenue, current	40,642	23,514
Operating lease liabilities	5,649	5,804
Other current liabilities	3,515	2,682
Total current liabilities	68,869	59,963
Operating lease liabilities, net of current portion	21,530	23,277
Deferred revenue, net of current portion	141,770	163,207
Other non-current liabilities	1	1
Total liabilities	232,170	246,448
Stockholders' equity
Preferred stock, $0.0001 par value per share: 5,000,000 shares authorized; no shares issued or outstanding
Common stock, $0.0001 par value per share: 195,000,000 shares authorized; 54,982,399 and 54,533,798 shares issued, and 54,802,399 and 54,355,798 shares outstanding at March 31, 2020 and December 31, 2019, respectively	5	5
Additional paid-in capital	820,813	811,546
Accumulated other comprehensive income	694	107
Accumulated deficit	(586,945)	(549,221)
Total stockholders' equity	234,567	262,437
Total liabilities and stockholders' equity	$ 466,737	$ 508,885