Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 31,791	$ 35,891
Short-term investments	166,299	188,743
Prepaid expenses and other current assets	3,075	6,431
Income tax receivable		35
Total current assets	201,165	231,100
Property, plant and equipment, net	9,728	3,882
Long-term investments	5,034	11,973
Operating lease right-of-use asset	12,872	14,137
Other assets	258	258
Total assets	229,057	261,350
Current liabilities:
Accounts payable	4,264	3,087
Accrued liabilities	4,333	3,305
Lease liabilities, current	2,575	2,483
Total current liabilities	11,172	8,875
Lease liabilities, non-current	10,932	12,244
Total liabilities	22,104	21,119
Commitments and contingencies (Note 8)
Stockholders' equity:
Preferred stock, $0.01 par value; 200,000,000 shares authorized as of June 30, 2020 and December 31, 2019; 0 shares issued and outstanding as of June 30, 2020 and December 31, 2019
Common stock, value	242	240
Additional paid-in-capital	350,019	347,089
Accumulated other comprehensive income	296	43
Accumulated deficit	(143,668)	(107,205)
Total stockholders’ equity	206,953	240,231
Total liabilities and stockholders’ equity	229,057	261,350
Non-voting Common Stock
Stockholders' equity:
Common stock, value	64	64
Total stockholders’ equity	$ 64	$ 64