Liquidity (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2020	Jun. 12, 2020
Subsidiary, Sale of Stock [Line Items]
Net loss	$ 6,397,000	$ 5,566,000	$ 14,137,000	$ 12,947,000
Net cash used in operating activities			11,030,000	$ 13,300,000
Unrestricted cash and cash equivalents	16,900,000		16,900,000
Shelf registration
Subsidiary, Sale of Stock [Line Items]
Sale of securities, authorized amount					$ 125,000,000
ATM Facility
Subsidiary, Sale of Stock [Line Items]
Sale of securities, authorized amount						$ 50,000,000
Amount remaining	47,800,000		47,800,000
Western Alliance Bank
Subsidiary, Sale of Stock [Line Items]
Line of credit maximum capacity	10,000,000		10,000,000
Line of credit current availability	3,800,000		3,800,000
Line of credit outstanding borrowings	$ 0		$ 0