Liquidity (Details) - USD ($) $ / shares in Units, $ in Thousands, shares in Millions		1 Months Ended	3 Months Ended	9 Months Ended
	Feb. 23, 2021	Jun. 30, 2021	Jun. 30, 2021	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020	Jun. 30, 2020	Jun. 12, 2020	Dec. 31, 2019
Subsidiary, Sale of Stock [Line Items]
Net cash outflow from operating activities				$ 19,219	$ 10,622
Cash and cash equivalents				33,102		$ 16,697
Restricted cash				200	$ 200	$ 200			$ 200
Offering costs	$ 100
Shelf registration
Subsidiary, Sale of Stock [Line Items]
Sale of securities, authorized amount							$ 125,000
ATM Facility
Subsidiary, Sale of Stock [Line Items]
Sale of securities, authorized amount								$ 50,000
Shares sold (in shares)		0.2	0.2
Proceeds, net of offering costs		$ 1,900	$ 1,900
Offering costs		$ 300	$ 300
Price of shares sold (in dollars per share)		$ 10.56	$ 10.56
Amount remaining				47,800
Liquidity
Subsidiary, Sale of Stock [Line Items]
Line of credit assumed				$ 7,000