Leases (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Leases
Operating lease cost	$ 136,000	$ 158,000	$ 438,000	$ 445,000
Short-term lease cost	0	0	0	2,000
Variable lease cost	33,000	33,000	98,000	96,000
Total lease cost	$ 169,000	$ 191,000	$ 536,000	$ 543,000