Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Current assets:
Allowances for accounts receivables	$ 3	$ 6
Preferred stock, $0.001 par value
Preferred shares (in USD per share)	$ 0.001	$ 0.001
Preferred shares authorized (in shares)	5,000,000	5,000,000
Common stock, $0.001 par value
Common stock, par value (in USD per share)	$ 0.001	$ 0.001
Common stock, shares authorized (in shares)	100,000,000	100,000,000
Common stock, shares issued (in shares)	38,355,972	34,980,896
Shares outstanding (in shares)	38,355,972	34,980,896