Leases (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Leases
Operating lease cost	$ 136,000	$ 143,000	$ 302,000	$ 287,000
Short-term lease cost	0	0	0	2,000
Variable lease cost	33,000	32,000	65,000	63,000
Total lease cost	$ 169,000	$ 175,000	$ 367,000	$ 352,000