Leases - Lease costs and other lease information (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Lease costs
Operating lease cost	$ 492	$ 568	$ 988	$ 1,191
Variable lease cost	158	468	391	665
Short-term lease cost	46	107	83	202
Finance lease cost
Interest on lease liabilities	7	11	15	23
Amortization of right-of-use assets	29	29	58	58
Sublease Income	(52)	(52)	(112)	(118)
Net lease cost	680	1,131	1,423	2,021
Cash paid for amounts included in the measurement of lease liabilities operating cash flows from operating leases	$ 474	561	$ 961	1,179
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 1,348		$ 1,531