Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 110,835	$ 325,493
Short-term investments	493,038	307,827
Prepaid expenses and other current assets	6,832	3,972
Total current assets	610,705	637,292
Property and equipment, net	2,069	2,021
Restricted cash	210	210
Operating lease right-of-use assets	5,949	6,334
Other long-term assets	1,330	1,355
Total assets	620,263	647,212
Current liabilities:
Accounts payable and accrued expenses	22,139	23,024
Current portion of long-term debt	3,000	3,000
Total current liabilities	25,139	26,024
Long-term debt	3,500	4,250
Long-term operating lease liabilities	5,196	5,638
Other long-term liabilities	441	395
Total liabilities	34,276	36,307
Stockholders' equity:
Preferred stock, $0.0001 par value; 10,000 shares authorized; no shares issued and outstanding
Common stock, $0.0001 par value; 200,000 shares authorized; 66,263 and 66,194 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively	7	7
Additional paid-in capital	919,258	913,354
Accumulated other comprehensive income (loss)	(82)	46
Accumulated deficit	(333,196)	(302,502)
Total stockholders' equity	585,987	610,905
Total liabilities and stockholders' equity	$ 620,263	$ 647,212