Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 251,767	$ 294,972
Short-term investments	25,717	19,898
Accounts receivable, net	12,110	6,468
Inventories	24,554	18,384
Prepaid expenses and other current assets	7,578	6,189
Total current assets	321,726	345,911
Restricted cash	33,311	33,311
Property and equipment, net	15,548	14,998
Operating lease right-of-use assets	8,004	8,253
Other assets	1,240	1,356
Total assets	379,829	403,829
Current liabilities:
Accounts payable	6,651	4,948
Accrued compensation and related benefits	12,602	16,845
Accrued expenses and other current liabilities	8,183	7,903
Accrued warranty liability	2,860	2,913
Deferred revenue, current	3,540	3,201
Operating lease liabilities, current	984	882
Total current liabilities	34,820	36,692
Accrued interest, noncurrent	359	240
Deferred revenue, noncurrent	536	570
Operating lease liabilities, noncurrent	7,773	8,044
Term loan, noncurrent	29,696	29,674
Total liabilities	73,184	75,220
Commitments and contingencies (Note 6)
Stockholders' equity:
Preferred stock, $0.001 par value; 5,000 shares authorized, and no shares issued and outstanding as of March 31, 2021 and December 31, 2020
Common stock, $0.001 par value; 300,000 shares authorized as of March 31, 2021 and December 31, 2020; 42,888 and 42,722 shares issued and outstanding as of March 31, 2021 and December 31, 2020, respectively	43	43
Additional paid-in capital	830,694	822,624
Accumulated other comprehensive (loss) income	(8)	1
Accumulated deficit	(524,084)	(494,059)
Total stockholders' equity	306,645	328,609
Total liabilities and stockholders' equity	$ 379,829	$ 403,829