Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Current assets:
Cash and cash equivalents	$ 62,468	$ 39,181
Short-term investments	91,442	51,508
Accounts receivable, net	9,398	8,601
Inventories	10,946	10,322
Prepaid expenses and other current assets	3,443	2,878
Total current assets	177,697	112,490
Long-term investments	0	18,224
Property and equipment, net	2,824	2,734
Restricted cash	310	310
Other non-current assets	2,997	3,644
Total assets	183,828	137,402
Current liabilities:
Accounts payable	2,046	1,898
Accrued liabilities	13,008	15,034
Total current liabilities	15,054	16,932
Long-term debt	45,160	44,879
Other liabilities	3,876	3,700
Total liabilities	64,090	65,511
Commitments and contingencies (Note 7)
Preferred stock, $0.001 par value
Shares issued and outstanding: none	0	0
Common stock, $0.001 par value
Shares issued and outstanding: 33,889,077 and 31,255,267 at September 30, 2020 and December 31, 2019, respectively	34	31
Additional paid-in capital	341,687	263,384
Accumulated other comprehensive income	152	2
Accumulated deficit	(222,135)	(191,526)
Total stockholders' equity	119,738	71,891
Total liabilities and stockholders' equity	$ 183,828	$ 137,402