Leases - Lease costs and other lease information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Lease costs
Operating lease cost	$ 634	$ 602	$ 1,825	$ 1,772
Variable lease cost	223	222	888	633
Short-term lease cost	102	122	304	416
Finance lease cost
Interest on lease liabilities	10	14	33	45
Amortization of right-of-use assets	29	29	87	87
Sublease Income	(57)	(65)	(175)	(202)
Net lease cost	941	924	2,962	2,751
Operating cash flows from operating leases	$ 628	$ 600	1,807	$ 1,774
Right-of-use assets obtained in exchange for new operating lease liabilities			$ 1,531
Minimum
Finance lease cost
Initial or remaining lease term under operating lease	1 year		1 year
Initial or remaining lease term under finance lease	1 year		1 year